Driving the Model S costs you more than you think



kWh UsedWhen you fill up a normal ICE car you know exactly what your costs are for the fuel. With an electric vehicle it is not that simple. There is a charging efficiency factor that comes into play which means that that energy that your car may be telling you that it used could be quite a bit lower than your actual usage.

A while back I wrote about installing an EKM Digital Submeter on my NEMA 14-50 outlet to measure actual power usage of the Model S so I could compare that to the reported power used. I had just had the meter installed and collected some initial data about the charging efficiency based on a very short interval. Now I have more data and the loss is larger than I originally expected.

Model S charging efficiency is worse than you may think.

Test Setup

I charge at home 99% of the time. So far in 3 months, 7,500+ miles i’ve only used a SuperCharger once and a HPWC (at the Tesla store) twice. At home I have a NEMA 14-50 outlet installed by a licensed electrician. I’m using the factory supplied mobile connector as the connector/cable between the outlet and the car.

Added to that outlet is an EKM digital sub meter to measure actual draw from the outlet. That meter is accurate to within 1% and does not add any measurable load of its own.


On the “anniversary date” of taking delivery of my Model S I record a bunch of pertinent information and then reset the Trip A setting. Before driving the next day I record the reading on the EKM meter. That way i’ve got the mileage and the Tesla reported power usage over the period driven and the the actual kWh used to get back to the original charge state (90% for me).

This process will let me see a bunch of information I want to track over time:

  • Monthly miles driven
  • Monthly kWh used as reported by the Model S
  • Monthly kWh used as reported by the EKM meter
  • Monthly Average energy used

I plan on using this information to look at how average energy used changes as the months/temperature changes and perhaps as the Model S gets more miles on it. Unrelated specifically to the car, but useful in other analysis is my current “all in” cost per kWh from my electric company and the current local gas price i’d be paying if I had purchased another Acura. Those will both change over time too.

While I don’t drive consistently on any given day (test drives, special trips and the like), the numbers will average out and my driving style is not likely to change much after over 30 years of driving (yeah i’m getting old but the Model S makes me feel young again!). I also drive pretty consistent patterns of commuting with a lot of miles to the same places which helps average out the special trips to locations with different terrain/conditions.

Basically, while the conditions aren’t perfectly stable over time, the averages and data from this real world testing will be pretty accurate.

The Data

The last period (6/21 – 7/21) was my first full period with both the car and the EKM meter. A month of driving and charging, especially with the miles and kWh’s involved is a decent period over which to look at the results versus the 2 days from my prior blog post.

Here’s the data:
Actual Energy June-Jul

In the above table you can see that the Model S reported 728 kWh used during the period but the meter reported 894 kWh used. This means my charging efficiency is only about 82% and electric usage (and cost) is 18% higher than I may have expected based on the readings the Model S provides. For that month this is an extra $26 of charging cost which is a small number but a decent percentage of the total. The good news is that even using this larger kWh number, the savings versus driving my old ICE car for energy alone comes in at $334 — i’m saving $334/month in gas driving my Model S!

My electric cost is 18% higher than I may have expected based on the readings the Model S provides, but i’m saving $334/month in gas driving my Model S!


External research indicates that an average charging efficiency loss in the industry is in the 10-12% range. In the forums of the other EV vendors there are people doing a similar analysis and getting charging efficiencies close to 90% (10% loss) on both the Nissan Leaf and the Chevy Volt. Consumer reports also did a study on the Nissan Leaf and reported 85% efficiency although that test was short term and possibly flawed from that.

Average charging efficiency loss in the industry is in the 10-12% range

Over this one month period of over 2,400 miles i’m seeing an 18% loss using the standard home charging setup that Tesla recommends. Many people quote an 85% charge efficiency for Tesla, and Tesla’s own charging calculator appears to assume a 91% charging efficiency which is quite different than the 82% actual charge efficiency i’ve measured and  significantly worse than the average industry charging efficiency.

It would be great to see a Model S owner do a similar test with a HPWC setup at home to see if that HPWC is somehow more efficient (it likely is) and gives results closer to what Tesla is providing. I’d love to do the test but i’m not quite ready to shell out $1,200 plus electrician costs to get that data — assuming a cost of about $3,000 all in it would take me over 20 years to break even assuming the HPWC improves my efficiency by 10%.

From the results above, my conclusion is that the Model S charging efficiency using the standard home setup is 5-10% worse than other EVs on the market.

Model S charging efficiency is 5-10% worse than other EVs on the market.

Does Tesla have better battery technology, or is this just a battle of size? More to come on that front.

TuneIn Radio on the Tesla Model S


A while back I wrote about both Slacker Internet music and AM/FM Radio on the Model S and TuneIn Radio is an interesting combination of the two bringing some of the strengths of each while dropping some of their weaknesses. Similar to Slacker and AM/FM, TuneIn radio is a standard option on every Model S (at least in the US). There is another music/radio type option for the Model S with XM radio that comes with the premium sound system but I didn’t purchase that sound system and have yet to get a loaner with it activated.

As I said in my prior post, i’m not a huge radio or TV fan, but if you’re going to listen to Radio in the Model S, i’d recommend forgoing the AM/FM options and heading right to TuneIn Radio. That choice could possibly change if you have XM as an option but I suspect not given my prior history with XM reception.

I’d recommend forgoing the AM/FM options and heading right to TuneIn Radio.

TuneIn Controls

TuneIn RadioWhile the TuneIn control interface in the Model S is really well done, what stands out the most is the huge amount of stations available and broken down in so many different ways. You want to listen to country music from Norway? No problem! You could literally spend all your time in the Model S exploring station after station around the world in so many formats and languages that its amazing.

What stands out the most is the huge amount of stations available

To get to the music you select Internet from the music selection area and then pick TuneIn. You then get choices of your favorites, local radio stations, stations by type (music, talk, etc.) and by location. Each area is rich with a ton of stations. For example, I couldn’t find a local AM or FM station I knew about that wasn’t also on TuneIn.

But the real benefit was that I could find stations that friends and family listen to all the time from different areas of the country that i’ve also come to love from visits to them. I can listen to the same station that my in-laws are listening to in Pittsburgh when they ping me about a new song that just came on — you just can’t do that with normal radio. I can also pick up a Pittsburgh Steelers game which you won’t find broadcast in New England much. The Steelers don’t do much for me since i’m not a sports fan, but they sure make the wife less grumpy about not getting to drive!

After you’ve found that favorite country station in Tanzania (no kidding, there is one), you can favorite the station and come back to it later in My Favorites. For convenience the local stations are also gathered in a section. Once you pick a station the interface looks very much like the interface for standard radio. The forward/back controls skip you forward/back stations in the same category area (i.e. your next favorited station, or next local station). There’s album art and song information shown for the music playing most of the time or for the station when it can’t find anything. What’s also really nice is you can actually pause TuneIn radio for a call or a pit stop and then pick back up with the radio which you can’t do with AM/FM radio even in the Model S.

Internet Radio Benefits

TuneIn PlayingLike standard AM/FM radio, these are radio stations and they have the DJ’s talking, radio ads, and all sorts of other stuff. If you’re looking for entertainment, traveling company or news and information then this kind of radio format over Slacker or your USB music library is going to be great for you and there’s a lot of choices available.

Other than the broad choices, another great option is that Internet radio sounds better. You need a working 3G connection (standard in every Model S) and be somewhat near civilization. For me 3G is generally more reliable than AM or FM in my area, but what contributes to this sense of reliability is that the car can buffer (or save up) a section of the music for those intermittent periods where it loses connectivity — music doesnt skip or fade in and out with Internet radio. This means all those stations you could barely receive on standard FM that frustrated you with HD/SD quality changes or that you got a ton of static with you can get through Internet radio and the quality and reliability is better.

Music doesnt skip or fade in and out with Internet radio

Perhaps it’s me, but listening to static in the Model S just doesn’t seem right. Static on my sound system should be a thing of the past — and it is with TuneIn.

Better radio, but still radio

TuneIn radio is still radio and i’m not a huge fan of the format with ads, etc. But, if i’m going to listen to radio on the Model S its going to be via TuneIn. The standard AM/FM radio area is a waste of time but for long trips when i’m looking for something to break up the monotony of book tapes or my (overly country!) music library I could kill some serious time with TuneIn and the massive collection of stations and formats.

It would be interesting to see what the interface looks like for XM radio for those that got premium sound. I had XM on my Acura for the first few years and dropped it — many XM stations have ads on them (and you’re paying for the service), and XM radio cuts out if you can’t get line of sight to the satellites (bad weather, overpasses etc.). I strongly suspect that TuneIn is the best radio experience on the Model S.

TuneIn is the best radio experience on the Model S.

Tune in to AM/FM Radio on the Model S


I’ve never been a huge radio or TV fan — I just can’t stand ads. Thats one reason i’m a big fan of the Slacker internet music offering on the Model S. With Slacker you have more input over your preferences and there are no ads. With Slacker you can skip to the next song, pause the current song, and you can indicate that you like or dislike a song. With the radio offerings you can only change the channel.

All that being said, as I settle into the Model S I wanted to explore every area and so I spent some time with both the standard and internet radio offerings. I’ll cover the standard radio offering in this post and the internet radio offering in my next post.

AM/FM Radio Controls

FM RadioTesla has done a really nice job on building an interface to AM and FM radio in the Model S. With the radio interface you get a standard tuning dial you can swipe your finger over to tune up or down bands. The seek right or left buttons search for stations with good signals. Like many cars you can press to set/save a station for later.

Tesla has done a really nice job on building an interface to AM/FM radio in the Model S.

The Model S supports both “standard” and HD radio which embeds a digital signal in the AM or FM bands that provides extra information. HD radio allows stations to offer multiple formats or programs at the same time on the same frequency. In the photo i’m tuned into FM 102.5, but I have 2 stations there I can pick from, each playing something different but run by the same station. From what i’ve read you can have 3 full HD channels at the same frequency and i’ve found stations in my area that offer that. The other advantage that HD radio has is that with the digital song information provided the Model S can provide cool things like cover art that you can’t easily get on standard radio.

The user interface appeared to be the same on AM and FM although I was unable to find AM stations that showed me things like cover art or alternate channels but I did find HD AM channels.

Overall the interface was clean and friendly and super-intuitive.

AM/FM Reception

Other than the HD version which was new for me, these are the same radio stations you listen to anywhere, and they have the same age-old location and reception issues.

While I live in New England in a pretty populated area of the country, broadcast signals are spotty at times. AM is particularly bad in most places and even popular FM stations can be spotty at times. In my experience the Model S is worse at radio reception than other cars i’ve previously owned, most notably for AM radio. I had a slight buzz in the best AM stations on acceleration and a loud buzz in regen-assisted deceleration on the AM stations. This was pronounced enough that I added it to my list to have Tesla Service look into next time I have the car in, but I strongly suspect this is a design, not implementation issue.

The Model S is worse at radio reception than other cars i’ve previously owned

For FM, I had no interference from acceleration or deceleration but there were very noticeable constant switch overs between HD and “standard” radio that was annoying with the end result being that I had to turn off the HD stream. For those not familiar with HD radio, these cut-overs and cut-backs only work on the primary stream. For instance if i’m listening to 102.5 #2 and the reception cuts out I get nothing. It can only fall back to standard radio when i’m listening to the #1 HD station.

Still Radio

This may be obvious, but this is still radio. You’re inundated with ads, radio station ID notices, commentary from the DJs, etc. For some that’s added company and entertainment, but for others its a necessary evil to get to the music. In the new age of Pandora, Slacker and huge digital music libraries it’s really difficult to go back to regular radio, especially given the reception issues above which are mostly not specific to Tesla but the nature of standard AM/FM radio. When was the last time you watched TV that came in over an antenna?

Fortunately for those that want the commentary, talk shows and the like there’s an alternative on the Model S — TuneIn radio which i’ll cover in a different post.

Unless you’re in a place where your Model S has no 3G reception but you can somehow receive decent AM/FM stations (seems unlikely, but Northern California is pretty barren for cell phone signals from my experience), i’d skip the AM/FM radio completely — while the user interface is really nice, AM/FM radio is all but dead.

While the user interface is really nice, AM/FM radio is all but dead.

Tesla’s Subzero Weather Package



It may seem odd to you that i’m writing about the Subzero Weather Package for the Model S when its summer time in the US, but if you lived in New England you’d understand. On July 4th the family decided on a road trip to Rockport, MA which is 180 miles round trip from home. This post isn’t about the Model S’s amazing range but how the subzero package kept complaints to a minimum and saved me some money.


Subzero PackageThe Subzero weather package is a $750 option at the time of purchase and I haven’t heard of any possibility of retro-fitting the option. While the Tesla site shows a car driving in the snow as the default image for the picture, the package has very little to do with driving in the snow. The alternate picture shows a better representation of what you get — heaters for things.

One thing to note is Tesla calls it “Cold Weather” in the controls but the package is called the “Subzero Weather Package.” I don’t believe the “Cold Weather” option turns up in controls for Model S’s without the Subzero package as every Model S comes standard with front seat heaters and controls always available at the bottom of the 17″ screen.

With the Subzero package you get 3 additions:

  1. Rear seat heaters
  2. Wiper blade defrosters
  3. Washer nozzle heaters

Seat Heaters

The main reason I bought the subzero package is that I live in New England and anything that can help with the winters is worth it! But seriously, my family loves seat heaters. My wife never drives without one on to help her back issues. One of the reasons I chose my old 2007 Acura MDX when I got it was it was the only car I was considering that had rear seat heaters and my daughter was all over that.

The Model S takes seat heaters to a new level.

The Model S takes seat heaters to a new level by providing 3 seat heater positions for the rear. Each one can be independently controlled  and set to off or a level 1-3 heat setting. From off, tap once to go to level 3, then tap again to go to 2 etc. One thing that would be nice is if they provided a quick “off” ability. I’m always doing extra tapping to go from 3 to off. A long press maybe?

Tesla should provided a quick “off” ability for the seat heaters.

When I first took delivery, only 1 of my 5 seat heaters worked. A reboot fixed that and they’ve been fine since. The seat heaters work amazingly well and its no wonder that Tesla recommends using them to deliver heat versus cranking up the cabin temperature as its a much more efficient method of getting warm.

Other than the quick “off” ability i’d also like to see these cold weather elements controllable from the app so I could warm my seat as well as my cabin before entering. Another annoyance is that Tesla, in their minimalist no-buttons approach, decided not to provide the rear passengers control over, well, their rear. This means as the driver I get the constant requests to raise or lower the temperature on various rear seat positions (my co-pilot hasn’t been brave enough to touch the screen yet herself). Short of adding switches in the rear of the cabin (unlikely for Tesla, and not happening with just a software update), I don’t see this one getting addressed. They may want to consider how minimal their approach is in the Model X. SUV rear seaters expect control!

The Model S doesn’t provide rear seat passengers any climate controls.

So, back to why i’m writing this in July. The outing was great and Rockport, MA is beautiful, but in traditional New England form, right after the “Lobsta” rolls, it clouded over, dropped to 65 and rained all over us. I had my handy one-person umbrella stuffed in my glove box but otherwise we were unprepared. After an hour of shopping in the rain and holding off on expensive sweatshirt purchases, the seat heaters earned their keep. All 5 were blazing on the way home as we were drying and warming up. Seat heaters are not just for the winter months and can help loosen up a stiff back, take some boredom out of a long drive, and warm you up when you’re physically or mentally cold.

Wiper Heat

Heated WipersThe other two options that come with the package are related to your windshield. One Tesla calls “Wiper blade defrosters” is a set of heating elements that are part of your lower windshield that warm up your wiper blades to stop them from freezing to the windshield. They’re also supposed to help remove ice from the wiper blades but i’ve heard mixed reviews on that front. The heating elements are separately controlled by touching the dash area in the picture above. Like the seat heaters, this is not controllable from the app and would be another useful thing to turn on long before reaching the car. Also beware that these heating elements automatically turn off after a period of time so you may need to periodically turn them back on if you still need them to do some work.

Beware that these heating elements automatically turn off after a period of time

I never noticed it until I was writing this post, but did you notice that the Model S’s frunk has no washer fluid dispensers to detract from its beauty?It turns out they’re tucked under the edge of the Frunk close to the windshield:

Heated Nozzles

This placement will make them less prone to getting a lot of ice and snow build up on top of them, but snow and ice can slide down into that area. The third option that comes with the subzero package is a heating element to keep these free of snow and ice and by all reports it does a pretty good job at that.


If you live in a cold or seasonal climate then the subzero package can be very useful and while I have yet to put this package to real use in the winter, i’m getting use out of it all year long. Unlike the Premium Lighting package, it’s more reasonably priced and actually provides a tangible benefit. Missing from the package are controls for the passengers and extras like a heated steering wheel that comes standard on many premium sedans these days. While Tesla has been a strong seller in warmer climates like California, their cars have done well in tough Norwegian winters too. About 26% of buyers purchase the subzero weather package and, despite its shortcomings, i’d recommend the subzero weather package — your friends and family will thank you.

Despite its shortcomings, i’d recommend the subzero weather package

Tesla’s 2014 annual shareholder meeting and coming features


2014 Annual Shareholder meetingI finally found a chunk of time to sit down and watch Tesla’s 2014 annual shareholder meeting. The video was posted June 5th. While there’s interesting stuff throughout the video I wanted to just focus on the hardware and software features mentioned in the video. The features section is fairly short and starts at 13:07 into the video and runs through to 15:49 if you want to get Elon’s words directly.


Elon said that you’ll be able to personalize the car a lot more from small things like naming your car and seeing that name in the Tesla portal and app to more advanced personalized learning behavior. Not a lot of detail was provided around the personalized learning, but he did mention calendar integration and providing a heads up on traffic and commute times to upcoming scheduled appointments. This sounds sort of like what you get on iOS or Android when you look at your day view and hopefully it will include other things included there like watched stocks, weather, etc.
Continual flow of updatesTraffic optimized directions,  re-routing around traffic, alerts for upcoming traffic are all also coming. The intelligence for this is from both a collaborative network of other Model S cars on the road as well as external data sources (he said 20 million other data sources). Obviously, with only 40K cars sold and only 900 in the New England area a GPS system based on low numbers like that is not going to be very effective. The Model S network data will be given preference/priority over the other data sources, but it won’t be the only source and I sincerely hope some of those other data sources include Google traffic. He compared the collaborative network between the Model S’s to Waze. That implies some interaction possibilities like speed trap reporting, road closures, etc. The traffic re-routing will be a great addition but a more interactive environment between Model S’s really opens up some interesting possibilities for the future.
One flier that Elon threw out at the very end (~1h10min mark) is that he’s confident that is less than a year you’ll be able to go from highway onramp to highway offramp without touching any controls. Their dates aren’t very believable and its not clear if he’s just talking about the possibility of doing this (Google already can do this sort of thing) or if he meant this would be available in a Tesla product. Either way it will be an exciting (and probably scary) next step in the driving experience!


It should be no surprise to most that Tesla does not have model years but rolls in changes as they’re needed. Elon cited several cases of improvements made to the seats and undercarriage (Titanium). In addition he mentioned several new features that were introduced like power folding mirrors and parking sensors. The only real “hardware” upgrade he mentioned that is coming later this year is another seat option. It sounds like the current seats will remain standard and this new seat will be an upgrade option that can be retrofitted into existing Model S’s for a cost. I’d expect the new seats to be a significant upgrade, but i’m quite happy with the current ones I have and I spend about 2 hours a day in the driver seat.


There wasn’t a lot of really new news about features in this shareholder meeting but there were some good clarifications. The collaborative network part between Model S’s was the most exciting and something I hadn’t heard before — I had assumed they would just use Google traffic alone. The other items like upgraded seats and a more personalized experience are also interesting.
In terms of a delivery timeline, Elon said it was “Rolling out fairly soon” but given their poor history on date estimates it’s anyones guess what this means.


Model S Tire Rotations



The Model S is a very unique car and both the car and Tesla make for different tire experiences than you might have with a standard car. The Model S is insanely quick and all this power translates to your tires. The Model S is also heavier than a normal car thanks to the amazing battery that powers it — this translates to extra force on your tires as you round corners. The Model S recharges itself as you decelerate using regenerative braking — this translates to reverse force on your tires. To counter some of these extra forces Tesla has modified the way the wheels are angled on the car (camber, tow in and other things I know little about). To improve range they’ve include low rolling resistance tires. All of these factors add up to some special tire care that you may not have perviously been exposed to.


First, all my experience and research has been with the standard 19″ wheels and the Michelin Primacy MXM4 all-season tires that came standard with my car. While some of this will apply to the 21″ high performance tires too, I recommend you do your own research with those. You will get much less mileage out of the 21″ tires. With the “W” rating on my standard tires, they have a manufacturer tread wear warranty to 45,000 miles. On my 2007 Acura MDX SUV I got an average of 53,000 miles on a set of tires and after some research i’ve decided i’ll be happy if I get 40,000 out of the tires on the Model S.

I’ll be happy if I get 40,000 out of the tires on the Model S.

From the owner’s manual, Tesla recommends rotating the tires every 5,000 miles (8000 km). They specifically tell you not to rotate tires on the Performance Plus models, so beware those differences. With most gas-powered cars they generally recommend rotating your tires every other oil change, or about every 10,000 miles. So the tire rotations on the Model S are much more frequent.

Tire rotations on the Model S are much more frequent.

Special Considerations

Directional TiresThe tires on the Model S are what they call directional tires — they’re designed to roll in a specific direction. This means when you rotate tires you keep them on the same side of the car and swap the front left tire for the rear left tire and then do the same on the right side. The picture to the right is Tesla’s recommended rotation pattern.

Due to the weight of the car, the nuts on the wheels are tightened more than most cars and this specification wasn’t in any of the manuals I received. After some research, whether you have the 21″ or 19″ wheels, Tesla recommends 175Nm or 129lb/ft of torque for the wheel nuts. Not all shops will measure this and be precise but with higher performance cars its important that the setting is reasonably close to the recommendation and consistent.

Lift pointsWhen the car is lifted you also need to be careful that they use the designated lift locations on the car so that they don’t damage the battery. That battery costs about $40,000 and the warranty does not cover damage due to improper lifting so you really want to make sure it’s not damaged when the car is lifted. Most shops will need to make some minor adjustments to line up their lift to properly lift the Model S at the designated locations, but properly warned this is not a big deal for them. The picture to the right (also from the owner’s manual) indicates the proper lift locations. They key point is those are on the frame and not on the battery.

The warranty does not cover damage due to improper lifting so you really want to make sure it’s not damaged when the car is lifted

Service Center

I drive a lot with about 2,600 miles added per month. That means i’ll need a tire rotation every 2 months if I follow Tesla’s recommended tire rotation schedule. When I hit 5,000 miles on my Model S I reached out to Tesla to ask them about the process. Their first response was:

You can get tire rotations done at any tire shop

I’ve had some bad experiences in the past with non-dealer shops and asked them for a recommended tire shop and got back the unhelpful corporate response:

Unfortunately, we cannot recommend third party service centers.

Frustrated, I reached out to fellow local Tesla owners via the TMC Forums and got a few local recommendations of the usual sorts like Town Fair Tire, Direct Tire, NTB, etc. None were strong recommendations (i.e. no local owner had used these themselves) and the internet reviews were a very mixed bag leaving me nervous about quality, cost and wait times.

I reached back out to Tesla and let them know I wasn’t really comfortable with a third party tire shop and they said I could bring my Model S to Watertown on a Saturday AM and wait for service with a first come, first serve sort of process. The Watertown service center is 60 miles from my house and my Saturdays are full so that wasn’t going to work for me. When I pushed on this they offered to send a Ranger to service my car. This sounded involved and possibly expensive (I didn’t ask) and i’m going to have to do this all the time so I chose to look around a bit more.

My take on all this was that the Service Center is really focussing on deliveries (the Watertown Service Center is also the only local Delivery Center) and real issues that need Tesla expertise and tire stuff is something they only do reluctantly or when they’re working on other things too, although they were not very upfront about this. I don’t blame them for focussing on more important things, but they should change their policy to allow them to recommend some trusted tire shops.

Tire stuff is something they only do reluctantly or when they’re working on other things too.

I brooded on this dilemma for a while then came up with a crazy idea. I know the service people at my local Acura dealer well — they’ve serviced my Acura for 7 years with oil changes, tire rotations, various engine/belt related matters, etc. I trusted them and they did a good job. They were always encouraging me to bring my other car makes there for service. I called up Joe at Acura and explained my situation and he scheduled me for an appointment with less than 24 hours notice — a far cry from the 3 week scheduling for service Tesla currently has in our area. Scale matters.

Tesla should change its policy to allow recommendations of trusted tire shops.

Tire Rotation

I went to the Acura dealer well armed. I printed out the tire rotation pattern, the indicated lift points, and wrote the nut torque on the sheets. Then I spoke to the service manager then the mechanic to make sure they understood it all. They were excited to see the car and learn about it and I had many Tesla moments.

The actual rotation didn’t take very long, less than an hour from the time I arrived and much of that time was them learning about the Model S (they were baffled by the inability to turn it off), adjusting their jack system to jack in the right spots and a test drive.

I monitored the car from the Tesla app during the process and watched the car zip down the street at the end of the service. I won’t say if they did anything illegal when they “tested” the tires, but I will say that the mechanic came back with a huge Tesla grin on his face and told me what an amazing car it was which was the best part of the entire process.

The mechanic came back with a huge Tesla grin on his face.

The whole process of scheduling the appointment, getting the rotation done and paying was easy and I trusted the team. The total cost was $31 which is less than many places would charge.


Tesla is still a small company with not enough service centers or employees to keep up with their amazing growth. While the Model S doesn’t have a lot of normal maintenance that needs to be done, tire rotations are something you’ll have to deal with and Tesla isn’t well prepared for this maintenance volume in all areas. For me the solution was to use my old trusted dealer for this basic maintenance. Many people own more than one car and this may well be a viable option for them too. While i’m sure some tire-specific places will do a perfectly reasonable job, I wasn’t ready to trust my $100,000 car to someone I didn’t know or have strong recommendations for and when they would have to deal with the few oddities of the Model S.

I wasn’t ready to trust my $100,000 car to someone I didn’t know

I’ll be back to Acura in a couple months for my next rotation and to catch up with my friendly service manager. I don’t get to see him much any more now that I own a car that is almost maintenance-free.

p.s. Elon, you got rid of the engine, can you eliminate tires next?

Tesla Model S Coat Hooks Review



Evannex HookUpBefore I bought my Model S I discovered that oddly Tesla had decided not to provide coat hooks in the car. While I don’t hang jackets very often, coat hooks are definitely a useful feature when you need them and I went looking for a solution. At the time there were very few options and people were using all sorts of solutions like double sided tape, felt hooks not designed for the purpose, and other odd approaches. The best option I found back then was the E-James which was 19.80€ (about $27 US) and I couldn’t figure out how to order it online since it was in a foreign language so I just gave up on the whole idea.

That was until I saw Evannex, probably the leading company focussed on Tesla aftermarket products, offer their HookUp coat hooks for a very reasonable price of $8.95 for a set of two. This looked to be a great solution and I was eager to try them out. One caveat though, the HookUp coat hooks are only available for models that have the panoramic roof option to provide the needed seam for installation.

 Initial Impression

Coat HookPackaging was simple with instructions, the two hooks and a Evannex brochure delivered in an envelope. The hooks look to be very well made and built specifically for their advertised purpose – hanging things in the Model S.


While there’s an installation page, installation is dead simple and requires no skill at all — a child could install these. No tools are required, the installation isn’t permanent and you can easily install and uninstall them when you see fit. I thought the ease of install and uninstall to be a great feature — if you don’t like the look of them when you’re not using them just store them in your glove box until you need them. 10 seconds and they can be installed again when you need them.

A child could install these

To install you sort of angle them 90% from vertical and slide them in-between the roof and the headliner and then twist and pull down slightly to lock into place. You can easily install these in 10 seconds. Before installing these I had never really looked at this headliner gap but it’s the perfect place for this hook.

You can easily install these in 10 seconds.

Below are some before and after pictures of the hook installation:

Before HookUp Installation

Before HookUp Installation

After HookUp Installation

After HookUp Installation


Hanging JacketTo test the hooks I tried a few different types of garments both with coat hangers and without. I tried my normal sports jacket, one of my wife’s dresses, and then a really heavy leather bomber jacket.

One of the things Evannex cautions about is to not exceed 4 pounds per hook. There’s no metal or anything along that headliner ridge to provide strong support so you don’t want to pull down too hard on these coat hooks and stress the headliner. A few business jackets per hook, or a single leather bomber per hook seemed about right and was risk-free. I wasn’t going to stress the system and risk creasing/damaging my headliner.

Do not exceed 4 pounds per hook.

The hook easily handled my heavy leather jacket. Due to the weight of the jacket it doesnt hang well on coat hangers anyway so I just hooked into the loop on the jacket and it hung well. The hook can hang coat hangers, or anything that has a loop or it can hook on to. For my business jacket I tried it on the coat hanger and it hung lower and touched the seat but also hung well. Using the loop in the jacket raised it up off the seat for me. As with most cars, there’s a balance between more clearance and using coat hangers.


For scoring of the Evannex™ HookUp solution this is how i’d score it:

  • Durability – Strong ABS plastic with a decent thickness — your headliner will warp before you break these. 5/5.
  • Secure Mounting – Easy to take off and put on, but a bit loose when on without weight applied. 4/5.
  • Price – $8.95 is very reasonable especially considering other (worse) options. 5/5.


Frankly it’s hard to imagine them doing much better with this. The hooks are reasonably priced at $8.95 for two, they work well, are simple to install and remove and have reasonable limitations. Evidently i’m not the only one that thinks it since they’re currently sold out on the site. If you’re in need of coat hooks for your Tesla Model S i’d highly recommend ordering them when they come back into stock or filling out their contact form to let them know you’re interested.

NOTE: The HookUp coat hooks are only available for models that have the panoramic roof option.

TESLARATI provides impartial reviews and is in no way affiliated or paid by the vendor for the content that is produced.

Tesla’s Panoramic Sunroof


Panoramic sunroofWhile I don’t often drive with them open, I’ve always been a big fan of sunroofs in cars. Sunroofs seem to open up the cabin space and make things feel less enclosed. For me getting the Panoramic sunroof option was a no-brainer when I ordered my Model S but for others the choice is not that automatic.


The Panoramic sunroof is a $2,500 option on the Model S and for me represented about 2.5% of my total cost. Tesla claims it blocks 98% of ultraviolet light and 81% of  solar heat. I don’t know if those numbers are correct, but I can tell you that this is not your normal sunroof.

This is not your normal sunroof.

I love sunroofs, but my wife hates them. It’s always a discussion point when i’m buying a car. If it’s for me I get the sunroof,  if it’s for her we try not to. If she gets a car with a sunroof for some reason (“loaded” ones that have everything on them) then she pulls the shade over it and pretends it doesn’t exist. She dislikes the glare of the sun on her and the feeling of openness. I expected the usual complaints on the sunroof for the Model S and doubly so because the Model S does not include a shade for the sunroof which is unusual in my experience. Surprisingly she has never complained about the sunroof.

There is no shade for the sunroof

While the specs above about UV and light blocked sound cool, the reality is that the sunroof is so dark and so good at blocking light that it both meets my needs (more room, some outside light, openness) while meeting her needs too in not feeling too open or too glaring. This is the first car i’ve owned where we’re both happy with the sunroof.

This is the first car i’ve owned where we’re both happy with the sunroof.


Sunroof ControlsI had a loaner a while back and I wrote about the active suspension feature and to me it is mostly a gimmick with some cool show-off value. The sunroof is a great feature and has cool show-off value. There’s a separate section of your Model S controls dedicated to the sunroof if you have it. From there you can open the sunroof by dragging on the roof itself in the picture or by sliding the blue control to the desired setting. As the roof opens the picture updates showing the progress. Everyone always thinks its cool to be able to drag your finger and watch the progress while the mechanics are also going.

The sunroof is a great feature and has cool show-off value.

There are 4 key positions for the sunroof but you can also open to any setting you want:

  1. Closed
  2. Vent
  3. 80% open
  4. 100% open

Generally you end up using only positions 1-3. 100% open is ok if you’re sunbathing or parked but it makes a lot more noise than the 80% position when you’re driving.

Vent, unlike other cars, doesn’t do a simply angle the roof to lift the rear edge to provide some breathing room but does something more complex with the entire roof to provide the air. The vent setting looks like it would be a lot less susceptible to rain, dust, etc. than other car vent settings.

The vent setting looks like it is a lot less susceptible to rain, dust, etc. than other car vent settings.

Sunroof scroll wheel controlIn addition to the controls on the big screen you can control the sunroof with the right scroll wheel on your steering wheel. Select the sunroof setting then press to change and and scrolling the direction you want it to move. A second press on the scroll wheel will close or open it without you needing to scroll. So usually you just double tap the scroll wheel if you’re looking for a quick vent or close the vent operation.

If you use the Tesla mobile app you can vent or close the sunroof (but not open it) from the app wherever you are. This is useful if you left it on vent or open and a rain storm is coming in. Its also useful if you’re about to leave work and you want to let some heat out before you get to the car (turn on the A/C remotely too!). Tesla must have thought it a liability to allow you to open the roof remotely from the app so you can’t do that. But if you use Visible Tesla you can open or close the sunroof to any setting you want from your computer.

You can vent or close the sunroof remotely


The wind noise when the sunroof is in the various positions is what i’d expect based on my experience with other cars. This is impressive since the panoramic sunroof, even at 80% open, is much larger than most sunroofs. The 100% open position is the oddity since its much noisier and I don’t use that setting. 80% is like a normal sunroof being open. Opening the sunroof adds noise, but that is to be expected.

 Sound is impressively quiet with the panoramic sunroof, even at 80% open.

Sunroof sound baffleWhen the roof is open (not tilted) a sound baffle pops up to help with the buffeting noise you can get with open sunroofs. This baffle is larger than you see on most cars (to account for the large open area). I have 2 complaints with this sound baffle:

  1. I’m not real fond of the look of it since it stands up so much. Part of the tradeoff for the noise reduction.
  2. It’s made of cloth/fabric and collects bugs/pollen. Look at the the close up picture and think about me not using it very often. Its very dirty and hard to clean.

It has to be large for the size of the sunroof. It has to be fabric because its large. But the combination doesn’t work well for looks or maintenance.

Another thing that i’ve noticed on my Model S is that when the sunroof is open (vent or 80%) and i’m on back roads it rattles a bit more than i’d expect. Since thats basically the only time I would open the sunroof I think thats odd. I’m assuming something just needs to be adjusted/tightened and next time I take it to Tesla for some reason i’ll have them check that out.


One thing many Model S buyers are not aware of is that the sunroof actually provides some functionality thats pretty unrelated to the sunroof. While it may seem odd, you can’t put a bike rack like the Whispbar on top of the Model S without the sunroof. The reason for this is that without the sunroof the roof of the Model S is seamless both inside and out and that leaves no grooves, edges or other locations for third party products to latch on to. This is both true of the outside and the inside so any aftermarket solutions like coat hangers won’t be possible either unless you have the sunroof.

Aftermarket additions to the Model S are more limited without the sunroof.


As I said at the start, the sunroof was a no brainer for me, but if you’re on the fence, or even if you usually hate sunroofs on cars, you should take a second look at the Model S Panoramic sunroof in person. It is not your normal sunroof and can potentially provide unexpected benefits in the future. This is a feature you should not quickly dismiss when ordering your Model S and, unlike other features, there’s no chance they can retrofit this one after you take delivery.

This is a feature you should not quickly dismiss when ordering your Model S.

Tesla Over the Air Software Update


Update NoticePerhaps only geeks appreciate this, but I was excited the other day to see a software update notification pop up on my Model S. Most software updates for products are minor fixes and tweaks but sometimes they include new and exciting functionality and Tesla is no different. In the past we looked at Tesla’s frequency of updates and their contents, but this post is about the actual update process.


By all reports i’ve read that Tesla owners can get software updates over the air through the built-in (free) 3G internet connection that is included with every Model S or over a wifi connection if they’ve tethered their Model S to a wifi point in one or more locations. There are rumors that those with wifi connections tend to get updates faster than those relying only on 3G connections but that is difficult to prove.

Regardless of the connectivity, your Model S only notifies you once it has found and downloaded a software update. The notification is the one above. Note that it doesn’t provide anything really useful like the version number that is now available, release notes for that new update in advance of installing it, etc. Unless you troll the forums there’s no way to find release notes before you install. While Tesla does post release notes to your “My Tesla” account on Tesla.com, the notes lag far behind the date when the install is available.

Software update notices provide no useful information in advance of the update.

Watching the forums may give you a hint about what is available since Tesla staggers releases. Not everyone gets notified of an available update at the same time. Before I got this notice I was watching the forums and saw people reporting availability of 5.11 so I was anticipating an update notice soon for that update.

If you dismiss the notification you can make it come back up by pressing the Tesla logo at the top center of the 17″ screen. Otherwise you can start the install or schedule it to happen later.


Update Clock IconOnce the car has the update and is ready to apply it, you can apply it immediately or you can schedule it for a certain time of day (not day of week or exact date). The car must be in park for the update to get applied (more on this later) and they say it can take up to 45 minutes for the update.

Since this was my first one, rather than apply as soon as I was parked for a good time, I scheduled a time 5 minutes in the future to watch the process.

Once scheduled, a new icon appears at the top of the 17″ screen that looks like a clock. This is the only time i’ve seen this icon appear. Clicking on it brings back up the scheduling options for the software update but otherwise it just reminds you that you have one scheduled.

Other than the limited scheduling options which didn’t seem very restrictive to me, the scheduling part worked as expected.

The scheduling part worked as expected.


Update Out optionWhen the update process starts it gives you a warning and an “out” to cancel if you change you mind — the car will be unusable for up to 45 minutes once it starts. After this countdown you get a small “Starting update” notification followed by an “Update in progress” notification. And thats about it for up to 45 minutes.

Most people would walk away at this point, but the engineer in me couldn’t do that so I sat in the car for the entire update. The best way to describe it is that its messy, like child birth. Your car is going to do things you didn’t know it could do. Its going to make sounds, flash lights, spin fans, gurgle and do all sorts of other scary things. (BTW did you know your glove box opening button is lit?)

The best way to describe it is that its messy, like child birth

There are a lot of components in a Model S. According to TeslaTap, there are 432 lights, 50 motors/solenoids, 52 processors and a host of other complex machinery in the Model S. Each one needs software of some sort to control it and then a test program to go with that for making sure things are running fine. While i’m sure the iPhone update is an impressive engineering feat, I doubt it holds a candle to the Model S’s.

While i’m sure the iPhone update is an impressive engineering feat, I doubt it holds a candle to the Model S’s

The whole experience was kind of disturbing and i’m not sure i’d sit through another. At one point in the process the dash said this:

Bricked?I’m thinking “Uh oh, I bricked my $100K car!” Rather than hopping on the phone with Tesla, I waited it out. 45 minutes had not passed. It would be ok. Those Tesla folks are brilliant, it will be fine.

It was. After 22 minutes of more frightening behavior including lost temperature readings, mismatched clocks on dash vs 17″ display, the sound of bakes tightening like clenched cheeks, and other exciting things it told me the update was successful.


Phew I lived through the update (no surprise really since Tesla has done at least a couple dozen software updates to an ever-increasing fleet of Model S’s). I had previously been on version 5.9 (1.51.94) and I was expecting to see version 5.11. So I was disappointed to see the same 5.9 release notes and a version 5.9 (1.51.109). Same minor release as before, just a few builds later. In my previous post I had assumed that Tesla did not do in-version updates (i.e. an update from 5.9 to a later 5.9) over the air, but I was wrong.

Without any hints in the release notes and without finding anyone else in the forums that had the same version and build as me I have no idea what Tesla did to my car. With all the openness around patents you’d think they could be a little more forthcoming with the changes they’re making to your car. I can’t say that i’ve noticed anything different since the update but I assume something was fixed or improved (or they just wanted to prove me wrong with the whole in-family update comment!)

I have no idea what Tesla did to my car

The elusive version 5.11 had not arrived and more than a week has passed without it appearing. I’d be happy to skip 5.11 anyway if I could head right to the infamous 6.0 update that Elon has been promising for quite a while. I make sure my Model S is on wifi every night and day just so ensure I don’t miss my chance at that most precious of things — an over the air software update for my car!

The most precious of things — an over the air software update for my car!

Measuring EV charging efficiency


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kWh usedOne of the things that many electric vehicle owners don’t know is that the energy the cars report they use isn’t the same as what they draw from their power source. For many EVs, about 10-12% of drawn electricity is lost during the conversion process from AC to DC charge. This means that beautiful screen and counter you may have on your EV dash showing kWh’s used cannot be converted directly into dollars spent for transportation just using your power company’s rate per kWh.

The energy that EVs report they use is less than what you’re paying for.

Problems calculating actual energy costs

For the Tesla Model S, there are several counters and charts available. The “Since Last Charge” section is a great automatic counter that counts distance, energy used and average energy per mile since the last time you unplugged. With judicious use of the trip meters you can measure energy used over specific time periods, but it’s difficult to match those periods up to your power company’s billing cycle.

“Since Last Charge” section is a great automatic counter

It is also difficult to look at energy bills from before you started driving an EV to those after driving the EV to find the difference and calculate the added costs of driving an EV. This requires good records keeping, consistent use of electric for everything but the EV over the compared period, as well as other factors like weather. With a great deal of uncertainty you can calculate the rough amount of added cost from driving the EV on a monthly basis, look at the miles driven during that month and do the math. For example, year over year I used an extra 641 kWh in May of 2014 versus May of 2013. The main difference was taking delivery of my Model S in April so I drove an EV for all of May. I’ve driven an average of 2,350 miles per month (30 day average) since I took delivery so that gets me to 272 Wh/mile. My Tesla is telling me i’m using more than 272 Wh/mile and it’s no surprise that this rough way of calculating is off.

If you use reported energy used for that “Since last charge” report above you’d think I consumed 10.6kWh and at an electric cost of $0.1670/kWh that it cost me $1.77 to drive those 35 miles. But this doesn’t account for any power conversion losses. Your actual costs for driving those miles are higher and it will vary by type of EV and how you’re charging your EV. A standard 110V wall plug in the US is reported to be much less efficient than a NEMA 14-50 connector.

Your actual costs for driving those miles are higher and it will vary by type of EV and how you’re charging your EV

Charging calculators like the one on Tesla’s site can take into account some of these factors. For example for 35 miles of range added it reports that you need 11.6kWh of energy. From the picture above I only used 10.6 kWh to drive 35 miles. This implies that the Tesla calculation includes an assumption of 91% efficiency on the charge but there are other factors that affect this kind of calculation like how fast/aggressively I was driving. Unfortunately Tesla does not disclose their assumptions for their calculators.

It’s not simple to calculate how much actual energy you’re using to charge your EV.

The Solution

EKM Meter installedThe solution for this is to put a kWh meter on the outlet where you charge your EV. There are many types of meters out there from basic kWh counters to advanced meters that can broadcast actual use over a wifi network, plot graphs, etc. After some research I selected a meter from EKM Metering. My electrician did some independent research and came up with the same one so I felt pretty good about my choice. To monitor my NEMA 14-50 outlet (the one Tesla recommends for most people who charge at home), I bought the Basic 100A kWh meter and an enclosure for it. Delivered, the parts were $142.

Installing the meter requires messing with 240V/50A circuits and re-cabling your outlet since power has to flow through the meter to the outlet. While I may have been able to do this myself, I chose to have an electrician do it. I’m glad I did. It took him 3 hours to do it and I was keeping an eye on things throughout. Part of the time sink was the improperly sized enclosure EKM Metering provides — there’s just not enough room in there to route thick electric cables easily. After some blood, sweat and modifications to the enclosure (not really expected when you pay $40 for a piece of plastic), he got it done. He charged me a rate of $50/hour which is reasonable in New England for a licensed electrician.

My total cost to buy and have a meter installed was $292.

The meter is the white box on the right above my NEMA 14-50 outlet.


EKM ReadingOnce installed you have a kWh meter that just counts kWh used. There’s all sorts of fancy electrical math around how it does the counting but important part is its really accurate and doesn’t impact the results much as it does the measurement. This counter is like an odometer. It counts up forever. There’s no reset, no “trip counter” equivalent. Its just a counter that counts up when power is being drawn. You know power is being drawn by the flashing red light on the meter — 1 flash = 1.25Wh used.

With this meter you can measure actual energy used over any time period but you have to record some things. I’ve only had the meter a few days but here are the the measurements and results so far:

kWh Results


The items in orange are calculations. So i’m seeing about 85% charging efficiency on my Model S which is quite a bit less than the 91% Tesla seems to be using in their online calculator. I think the young EV industry could use more education and disclosures in this area.

I’m seeing about 85% charging efficiency on my Model S

I’ll be doing longer term measurements with the meter. Accuracy over short durations like this can have a lot of variation. I also want to look at things like power draw differences at night over long periods with allowing the car to go to sleep or not. It will also be interesting to see if these numbers improve or degrade over time with use, software updates and the like.


The kWh meter is a nice addition to a charging setup and gives you a true picture of your energy usage for driving your EV. For many it is an added and unnecessary cost: at $0.167/kWh and 325 Wh/mile the meter plus installation is the equivalent of 5,380 miles of EV driving.

Simply add about 15% to reported energy used by your EV and you’ll be closer to the actual energy used and will have a better picture of your true costs per EV mile driven. Drive clean and drive smart!

Simply add about 15% to reported energy used by your EV and you’ll be close.


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