By on August 13, 2012

Tesla’s 10 minutes test drives have received a lot of flak in the press. The Fourth Estate (at least parts of it) is trying to get to the core of that car, and that is its stellar battery performance. What is wrong with the tried and true practice of having the car for the day? A weekend?  This would give a tester time to find out when the battery runs out.  300 miles as per Tesla? 265 miles as per EPA? How much as per reality? Until journalists drive the Model S more than just a few times around the block, we have to go the unorthodox route of asking an inferential statistician.

We know someone who has two Masters of Science degrees from two different graduate schools, and who worked as an engineer at a major component maker. Let’s call him Joe. For a number of reasons, he does not want his name to be known.

Joe, who calls himself “a believer in the promise of electric vehicles”  does not distrust Tesla.  He consulted the tables and graphs on the Tesla website and attempted to project measurements taken under ideal  conditions into the real world, an art and science any automaker should be able to master. Tesla says it tested its cars on level terrain, no wind, no AC/heat, windows rolled up, constant speed, 300 pounds aboard. Good. What happens if you turn the A/C on? What happens at differing speeds?  What happens in real life?

After crunching the numbers, Joe expects that  a Tesla Model S 85kWh driven at 80 mph and with A/C on, assuming less than idea driving conditions, will get about 150 miles. Then, there better be one of those Tesla Superchargers close. Even if there is, it will be an exercise in patience. Says “Joe:”

“My guesstimate would be that somewhere around an hour and twenty minutes would be required for a full recharge, which includes the time required to get to and from the station from the Interstate, and also assumes no one is ahead of you at the recharge station.”   

When the car is 4 ½ years old, that 150 mile range will drop to 139 miles, says Joe while still relying on Tesla-provided data.

On the probably more common 60kWh version of the Model S, the expected range under the less than ideal conditions drops to  114 miles, Joe deduces from Tesla data.

Tables for the expected Model S driving range can be downloaded here.  Joe also provides estimated fuel cost tables, which we did not cover her. Let’s just say that he does not buy into the 2 cents per mile claim. Here are Joe’s research notes, in case you need his rationale behind his projections.

All of this of course would be moot once real life driving tests are available that last longer than 10 minutes. Until then, we need to rely on Joe.

TTAC has been promised a test drive within the week, and we were told it would not last long.

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51 Comments on “Your Tesla Mileage May Vary: Scientist Projects Drastically Shorter Range While Journalists Wait For Test Cars...”


  • avatar
    Dr. Kenneth Noisewater

    With the Model S’s sort of power at a driver’s disposal, I would bet real electric mileage will run closer to 400-500Wh/mile, which in Texas would be more like 5-6 cents per mile when charging at home. Still, that’s an awful lot better cost per mile for ‘fuel’ than any 4-wheeled vehicle with comparable performance, and for the top 5% tax bracket it would make a very nice second/commuter car.

    • 0 avatar

      What is the cost per mile when the battery bursts into flames?

      • 0 avatar
        bikegoesbaa

        Presumably that would be covered by insurance, so it shouldn’t impact the cost/mile equation much either way.

      • 0 avatar
        Dr. Kenneth Noisewater

        You mean 2 weeks after the catastrophic accident that would likely cause a gas-powered car to ignite immediately, after spreading fuel around to create a fire that would prevent bystanders without nomex gear from going to help the occupants?

      • 0 avatar
        CJinSD

        Or when it’s range is uselessly low after 8 years and you need to spend $40,000 to replace the battery pack, adding 33 cents a mile to your running costs. Then there are the public charging rates, which a real car only needs to achieve 21 to 32 miles per gallon to beat before you consider the battery cost or the value of your lost time waiting for your car to charge. Electric cars are excellent markers of people you don’t need to waste your time talking to.

      • 0 avatar

        bikegoesbaa

        - I meant, if the battery bursts into flames and takes the rest of the car, the house and some of the neighborhood with it.

      • 0 avatar
        magicboy2

        No customer-owned electric car has ever had its battery burst into flames.

      • 0 avatar

        “Fisker has implied that the Texas owner of one of its Karma models committed “fraud” or “malicious intent” in blaming the luxury electric vehicle for his garage fire last week, after he had to rescue his wife, mother and child from flames that spread quickly to his house. According to a report by Autoweek, the fire started shortly after the owner, Jeremy Gutierrez, parked the Karma in his garage. Gutierrez left the vehicle, which he had purchased in April, without plugging it in. Within minutes he reportedly smelled burning rubber. ”

        Best thing about the internet is that searching for stuff takes but a second and you just highlight, push CTRL-C and CTRL-V to lay out damning evidence.

        Whether you blame the engine, or the battery, or the wiring, or the paint itself, nothing changes the fact EV’s suck.

      • 0 avatar
        jz78817

        “Best thing about the internet is that searching for stuff takes but a second and you just highlight, push CTRL-C and CTRL-V to lay out damning evidence.”

        You should be in journalism, what with your stellar inability/unwillingness to verify sources. Just copy and paste whatever you find online and call it “evidence.”

        I am well and truly dumbfounded.

      • 0 avatar

        Jz

        I am in Journalism!

        Address all questions or concerns to Jeremy Gutierrez.

      • 0 avatar
        sportyaccordy

        LMFAO!!!!!!!

      • 0 avatar

        Actually, the fact that Gutierrez smelled rubber burning just before he saw flames points away from the battery being the origin of the fire.

        There are hundreds of thousands of car fires every year. Three-quarters of highway vehicle fires resulted from mechanical or electrical failures or malfunctions. Since the Karma has a combustion engine the car has all the things that cause fires in conventional cars. No need to point fingers at the battery in the absence of any evidence pointing to it. Photos of the burned car clearly show that the fire was in the front right, nowhere near any of the electric drive’s systems. There is an intercooler there, and wiring for the headlights.

        Occam’s Razor says that the likely cause of this fire, and that of Gutierrez’s car, is one of the same things that cause most other car fires.

      • 0 avatar

        Rubber burning could be the hoses or insulation material.

    • 0 avatar
      TecnamTwin

      Tesla’s owners have been reporting greater than projected range with some owners achieving well over 300 miles; same with some who have driven the Tesla-powered RAV4 EV almost 140 miles on a charge. Owners of the Roadster have taken coast-to-coast trips. They did it, and so can owners of the better designed and more capable Model S. The Model S’s actual range varies according to use, but worst case scenarios predictions do not help anyone.

      Real owners usually love their cars and try to get the most out of them. They are a few Chevy Volt owners who have achieved 60 miles in all-electric mode. Most owners that I know exceed their cars’ stated range. The Nissan Leaf owner that I know achieved over 120 miles on a charge once and regularly exceeds 100 miles. Roadster owners have exceeded their cars stated range, and Model S owners will. These drastic range reductions predicted for the Model S have NOT been realized by the first crop of owners. Roadster owners have proven that there will be an approx. 80% drop in battery capacity in 8 years. The battery pack can be used for many years after that, if the owner so chooses. I still has an 80% capacity. The Model S battery is much more advanced and is more forgiving of misuse.

      Predictions mean nothing. Actual range that owners are achieving should be published. Check some of Tesla’s forums. Owners are loving their cars! They do what Tesla says they will do and in some cases, more. I know that this car can take me 200 miles on a charge at interstate speeds.

      Owners trying to get to a destination will not be traveling at 80mph. If I were to take a trip in my Model S, I would pre-cool it while it’s charging. Then I would travel at 70 mph and be easy on the pedal. There will be people whipping past me wondering why this dude is going so slow. I don’t care. I’m getting to my destination gas-free, stress-free, emission-free, and silently; and for only $6 worth of electricity plus whatever the charger costs. Charge time, it is definitely prohibitive to “1000 miles in a day” type road trips.

      Here’s a 800 mile trip in a Model S.
      6 AM drive for about 3 hours. Stop for breakfast and charging 10:30 set out again. 1:00 PM stop for lunch and charge. 2:00 set out again. 4:30 charge, eat dinner, and occupy myself. 6:00 set out again. 9:00 find a hotel and charge. Viola, 800 miles in an electric car on $24 dollars worth of electricity, plus what ever the charger costs.
      Prius: 50 mpg Gas: $3.30 per gallon; 16 gallons used; $48.40 Time: 10 hours drive time at 80mph; 30 min. for lunch; 10 min. for gas stop; 20 min. bathroom breaks; ETA 5:00 PM

      BTW, Any trip that takes more than one day by car, I’m flying.

      Most houses have two or more vehicles parked in front of them, and most owners already have two or more vehicles at their disposal. Using their other vehicle for the 1% of the time spent doing roadtrips and the highly efficient electric car 99% of the time is much more reasonable than driving a gas-burner 100% of the time because of the 1%; that is if cost is not the driving factor.

      • 0 avatar
        protomech

        “Roadster owners have proven that there will be an approx. 80% drop in battery capacity in 8 years.”

        That’s a neat trick, as the Roadster has been available since 2008.

      • 0 avatar
        TecnamTwin

        I said that Roadster owners have proven that there WILL BE an 80% drop in capacity after 8 years.

        They have been losing battery capacity at a rate that is consistent with an 80% drop in capacity after an 8 year timeframe. The batteries and the battery packs were put through extensive accelerated aging process and torture testing to determine their safety and viability of use.

        BTW, the Roadster has been around since early 2008.

      • 0 avatar
        TecnamTwin

        I said that Roadster owners have proven that there WILL BE an 80% drop in capacity after 8 years.

        They have been losing battery capacity at a rate that is consistent with an 80% drop in capacity after an 8 year timeframe. The batteries and the battery packs were put through extensive accelerated aging process and torture testing to determine their safety and viability of use.

  • avatar

    What are “less than ideal driving conditions”? I would have thought that a constant 80mph would still be very close to ideal, even with air conditioning on. Really bad conditions are stop and go traffic.

    Lowering speed to 75 would help a bit. That takes the worst case range from 150 to 166. This still makes it pretty tense for my 150 mile round trip to Miami. But what happens when my speed varies from 80 to 20, which is a true real world scenario?

    I wonder what kind of figures actual owners have been getting. There are a few of them out there. You would think that of 50 people one or two would share something – but if the news is bad, it’s worth noting that most of those 50 are probably Tesla shareholders … and major ones at that.

    D

    • 0 avatar

      Maybe Tesla makes you sign a non-disclosure agreement (including lending the car to third party journalists) when you buy one and it voids the warranty if you violate it.

    • 0 avatar
      magicboy2

      “Less than ideal conditions” means heavy climate control use, with heat costing more (a lot more, actually) than air conditioning. Stop-and-go traffic is actually not that bad for an electric car due to the regenerative braking.

      • 0 avatar
        fredtal

        I’d like to see a reference for heating taking more energy than AC. I figure I’m the worse candidate for hybrid/electric cars. A 32 mile commute, 55 average speed (often cruising at 65+), only 6 stops and heavy AC use in SE Texas heat. Unless I could test drive one for a week would I be comfortable enough ever owning one, let alone justifying the extra costs.

      • 0 avatar
        krhodes1

        I can guarantee you that it takes more energy to heat a car when it is 10F out than to cool a car when it is 100F out – and where I live it is 10F a whole lot more than it is 100F. It’s just that with an ICE you get heat for free, as it is just wasted otherwise. I suppose that the battery pack generates some amount of waste heat that could be used for cabin heating, but do they?

        Stop and go is probably near ideal – not much energy used as you aren’t going fast, plus you get regenerative braking. And you probably aren’t going very FAR. Worst case scenario will be 80mph on a cold winter’s day in the Northeast with headlights on and heater running full blast.

      • 0 avatar
        Truckducken

        Fred, the deal is that cooling via the air conditioning process is more efficient than heating via resistance elements because it’s a different mechanism. In the AC process, you’re moving heat around via evaporation and condensation, instead of generating it from scratch as in resistance heating. Now if you’re living in SE TX and never turn on your heat, then obviously you are spending more on cooling than heating. But that’s a climate issue rather than one of efficiency. Maybe we need an automotive equivalent of the heat pump for these electric and hybrid cars?

      • 0 avatar
        fredtal

        Are they really using resistance coils to heat car? Guess I’m too old as I thought they were still using hot water from the engine. Of course I guess an all electric car wouldn’t have hot water, but it should have some hot air from the motors and batteries.

      • 0 avatar
        redmondjp

        Yes, they are using resistance coils powered directly off of the main pack to make heat – how else would you do it? The motor and drive electronics are pretty darn efficient (80-90%) and there isn’t enough waste heat produced by them to warm up the inside of the vehicle in an acceptable time.

        My 1981 Jet Electrica 007 EV had a gasoline-fired (marine-type) heater in it. The former owners told me that the car got about 20mpg when the heater was used in the winter!

        My friend who owns a Nissan Leaf confirms that heater use significantly affects the vehicle’s range.

      • 0 avatar
        carve

        Are you sure they aren’t using a heat pump, with coils just for a backup? Seems more logical to me. That combined with heated seats should do you fine most of the time.

        We probably need to revisit the paradigm of blasting the whole interior with free heat. Heated seat and steering wheel should be primary, combined with carefully directed venting, like the Mercedes “air scarf” and ways to keep the drivers feet warm without heating the vacant passenger side. A thin deep-tinted set of windows made of light plastic that can be independently raised or lowered could be used to minimize or maximize heat gain, as well as act as double-paned insulation.

  • avatar
    Geekcarlover

    I’m not the person Tesla is marketing to, I don’t buy new cars and don’t see electric vehicles showing up on used car lots this decade. (At least not in sizable numbers.) However, I’d still like to see a more realistic test. I know it’s cost prohibitive for most websites and magazines, but I’m waiting for someone to do a CR type test. Basically buy one and drive it for a month.

  • avatar
    Sundowner

    realistically, this car could never be an ‘only’ car. Most people who pay $50k+ for a new car rarely have only one car, anyway. I could see a mid-upper level executive using this thing as a daily commuter, where even a 100 mile round trip charge should be more than sufficient for 98% of all commutes. Then take the wife’s Lincon TrafficCreator, er.. Navigator for the weekend trips to the Hamptons. Gotta sell that lifestyle…

  • avatar
    Hank

    “Tesla says it tested its cars on level terrain, no wind, no AC/heat, windows rolled up, constant speed, 300 pounds aboard.”

    This must be how the Elantra was tested, too, and this is why Sun Belt states are so skeptical. They almost *never* get to drive under such conditions. Heck, I can’t even drive with the windows up, no a/c in upstate NY 1/3 the year (and 1/3 the heater’s going strong). And we live in hills that have dubbed our town a mini-San Francisco. So come test the car out here in the real world BEFORE you print the brochures, Tesla.

  • avatar
    z. beeblebrox

    If the author really wanted to remain anonymous, I suggest you remove his contact info from his research notes (rationale link.) Hell you even left his email address in there.

    • 0 avatar

      Ha! It seems like this guy is famous among the Tesla circles, with a 45-page thread dedicated to him by the Tesla Motors Club.
      http://www.teslamotorsclub.com/showthread.php/672-Ken-Kent-Kerry-Beauchrt-Beuchert-Beuchrt-Biker-Rider-Krider

      • 0 avatar
        rolosrevenge

        Wait, TTAC thinks HE is a credible source? Why not just say that they dug up an anti-EV internet troll? This is about the furthest thing from a reliable source there is. The fact that plenty of people in Roadsters make single trips of 150+ miles on a regular basis with cars EPA and Tesla rated for less tells me that Model S should go further. Why not just wait until you get an actual car to test and then report the actual truth about the car, rather than someones speculation? If you want more speculative work, I have a Ph.D. in electrical engineering focusing on electric vehicle technologies. Will you write an article on my analysis if I give it to you?

      • 0 avatar
        Herm

        Beuchert has a pretty nasty reputation in EV circles.. probably a hater.

        The useful part of his review is that he presented the worst case numbers on a 85kWh Model S, that is good to know.. so plan your purchase accordingly, you still dont want an electric as your long range cruiser.. DUH!

      • 0 avatar
        joeaverage

        I’ve run across that Kerry character on many websites discussing EVs for several years. Always a variation on that same user name. Always some eccentric opinions.

  • avatar
    Glenn Mercer

    Hear hear Mr. Beeblebrox! TTAC, I was stunned to see this mistake! You are going to be as well known for leaks as GM? Fix quick!

  • avatar
    magicboy2

    Can’t we look at what owners of existing electric cars are getting in terms of “ideal” range versus range with accessories/non-ideal driving conditions?

    I can tell you that in my Volt (10 kWh usable), it goes something like this:
    “Perfect conditions” range: 50 miles
    Normal range in city driving, minimal climate control: 40 miles
    With moderate A/C (90 degree day): 35 miles
    With moderate heat (50 degree day): 32 miles
    With heat blasting the entire time (20 degree day): 25 miles

    • 0 avatar
      APaGttH

      What do you think of your Volt?

      I move in less than a month and my commute is going to be 5.2 miles one way. a Leaf or Volt is looking very attractive. Moving into new construction, already have the 240VAC in the garage (not the charger – just the available circuit).

      • 0 avatar
        magicboy2

        I love it, it’s a great car (objectively speaking, not just because its electric). It was an easy choice over the Leaf because I take occasional road trips. The leases are cheaper than ever now too.

    • 0 avatar
      Ron B.

      In the early 1970′s one of my tasks as an engineer was to maintain a fleet of electric trucks which were designed to carry one pallet of heavy steel and cast iron parts(sometimes up to 4 tons) . The figures you quote are identical to these trucks which had a bank of Ni Cad batteries. They were all built in the 1920′s.
      Nothing much has improved at all, and as with internal combustion engines the principle is exactly the same as it has always been,it simply looks different after 100 plus years.

      • 0 avatar
        Dr. Kenneth Noisewater

        What was the top speed on those trucks, did they have AC, heater, nav, etc?

        Everything’s exactly the same, which is why we have 50 pound laptop computers with 7″ CRTs and lead acid batteries.

    • 0 avatar
      Dr. Kenneth Noisewater

      Mine’s comparable, though a bit reduced as I drive in Sport/L at all times and hammer the go pedal mercilessly. At any given traffic light I will silently pull about 3 car lengths ahead of any car or truck to my side before they start to catch up or we hit the next light. I got about 29mi of indicated range today due to temps of about 106F and several longish stretches of highway at 85mph or so.

      Lifetime power use for my driving style and climate control so far is about 400Wh/mile. Only malfunctions I’ve had in the last year/11k miles have been a freeze-up of the nav system and a flat tire thanks to a large chunk of metal. 90+% electric miles.

  • avatar
    Polar Bear

    I was fooled by the 300 miles thing. Oh well. I guess I can look at electric cars again in 20 years.

  • avatar
    schmitt trigger

    “I suppose that the battery pack generates some amount of waste heat that could be used for cabin heating, but do they?”

    +1
    Hurry up to the patent office, before someone else steals your idea.

  • avatar
    stopcrazypp

    Rather than guesstimating (which is not scientific in any way despite having a scientist do it; first of which is the assumption that doing 80mph on the highway is representative of the driving of a typical owner), let’s look at what real owners are getting.

    After 367 miles of driving, Rod and Barbara got 338 Wh/mi average, which equates to 251 miles of range on a full charge (85000Wh / 338Wh/mi = 251mi). This is a mix of highway and city driving with two people and A/C on.

    PenguinOpus averaged 390 Wh/mi (217mi) over 7 days, 350Wh/mi (242mi) more recently.
    http://www.teslamotors.com/forum/forums/actual-miles-charge

  • avatar
    SunnyvaleCA

    Assuming you can always find a high-speed charger when you need one, the article implies 80 MPH cruising for 150 miles takes 1.875 hours followed by 1.333 hours of recharge time before you can get back to the next 150 mile stint. 150 miles traveled in 3.2 hours means an average of 47 MPH. So, this doesn’t seem to be a car for long road trips.

    The car doesn’t appear to be a “sports car” or “family hauler” with tons of cargo capacity, either.

    Nor does it appear an “economy car” with its up-front price.

    I guess that leaves “novelty car” and “luxury car.” Not sure how the luxury part works, but it is certainly a novelty car at the moment. The problem with that final designation is that the novelty wears off sooner rather than later.

  • avatar
    CapitalistOppressor

    Google “Model S Range” and the relevant blog post with picture of Elon Musk right next to it is at the top of the page labeled “Model S Efficiency and Range” which was last updated on June 7th just as the first production models were being built. The top of the second paragraph of that post links you to a detailed post on the physics of range in the Roadster. The rest of that paragraph tells why its important for customers to read both blog posts to understand range calculations.

    Both posts clearly state that high sustained speeds have by far the largest negative effect on range. Under the base conditions listed, driving 55mph gives you 300 miles of range, and driving 80mph gives you 200 miles of range.

    Elon also clearly states that extreme climate conditions can result in climate control losses of 10-15%. Those are already worst case numbers from a company that has vehicles with years of experience operating above the Arctic Circle.

    Mr Beauchrt applies a 10% penalty (already “extreme conditions” per Tesla) for heating and air for his mid range projections, then goes on to apply ANOTHER 15% penalty for.. more heating and air. Oh, and some undefined non ideal driving conditions that I take to mean blizzards or rain storms based on his discussion of extra rolling resistance and air resistance.

    I don’t like to judge people on their driving habits, but the basis of this entire post assumes that people should be worried about what range they will get in their new Model S while driving 80mph in a blizzard or rainstorm.

    If Mr. Beauchrt wants to dock an extra 15% from the range from Model S he should detail the actual driving conditions that produce that effect and justify his contention that people will be driving 80mph under those conditions.

    • 0 avatar
      Herm

      That extra penalty that he tacks on is for battery degradation after 4 years.. at least he did not extend it to 10 years or compare the total cost to a used Camry. Some people do that.

  • avatar

    That’s a BEAUTIFUL car. If only I could get my 6.1L Hemi with it.

    • 0 avatar
      joeaverage

      Nothing stopping you from buying one and adding the Hemi. No worse than updating a 1930s car with a modern driveline. We do it all the time. I’d like to have a Tesla S with a small quiet generator up front that I could install and remove easily. Would not have a problem at all leaving the ginny running to recharge the batteries in the parking lot if there was not a recharge station. I’d prefer a recharge station of course. Honestly the ‘S’ already goes anywhere I’d want to go with a car except the Gulf coast but then I rarely make that trek either.


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