Your Tesla Mileage May Vary: Scientist Projects Drastically Shorter Range While Journalists Wait For Test Cars

Bertel Schmitt
by Bertel Schmitt
your tesla mileage may vary scientist projects drastically shorter range while

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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4 of 51 comments
  • CapitalistOppressor CapitalistOppressor on Aug 13, 2012

    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.

    • Herm Herm on Aug 14, 2012

      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.

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

    • Joeaverage Joeaverage on Aug 27, 2012

      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.

  • Analoggrotto Only allow Tesla drivers to race, we are the epitome of class and brilliance.
  • Wjtinfwb When my kids turned 16 and got their Operators, we spent $400 to send both (twins) to 2 driving schools. One held by the local Sherriff was pretty basic but a good starter on car control and dealing with police officers as they ran the school. Then they went to a full day class in N Atlanta on a racetrack, with the cars supplied by BMW. They learned evasive maneuvers, high speed braking, skid control on a wet skid pad and generally built a lot of confidence behind the wheel. Feeling better about their skills, we looked for cars. My son was adamant he wanted a manual, Halleluiah! Looking at used Civics and Golf's and concerned about reliability and safety, I got discouraged. Then noticed an AutoTrader adv. for a new leftover '16 Ford Focus ST six-speed. 25k MSRP advertised for $17,500. $2500 above my self-imposed limit. I went to look, a brand new car, 16 miles on it, black with just the sunroof. 3 year warranty and ABS, Airbags. One drive and the torquey turbo 2.0 convinced me and I bought it on the spot. 7 years and 66k miles later it still serves my son well with zero issues. My daughter was set on a Subaru, I easily found a year old Crosstrek with all the safety gear and only 3k miles. 21k but gave my wife and I lots of peace of mind. She still wheels the Subaru, loves it and it too has provided 7 years and 58k miles of low cost motoring. Buy what fits your budget but keep in mind total cost over the long haul and the peace of mind a reliable and safe car provides. Your kids are worth it.
  • Irvingklaws Here's something cheaper, non-german, and more intriguing...
  • Wjtinfwb Happy you're loving your Z4. Variety is the spice of life and an off-beat car like the Z4 intrigues me as well. More than anything, your article and pictures have me lusting for the dashboards of a decade ago. Big, round analog gauges. Knobs and buttons to dial up the A/C, Heat or Volume. Not a television screen in sight. Need to back up? Use the mirrors or look over your shoulder. If your Z4 had the six-speed manual, it would be about perfect. Today's electronified BMW's leave me ice cold, as do the new Mercedes and Audi's with their video game interiors. Even a lowly GTI cannot escape the glowing LED dashboard. I'm not a total luddite, Bluetooth streaming for the radio would be nice and I'd agree the cooled seats would be a bonus on a warm day with the top down. But the Atari dashboard is just a bridge too far for me.
  • Craiger Honestly I was incredibly disappointed by the lack of steering feel. I dropped off my 530 at the dealer in New Jersey and picked up the Z. Driving all of my familiar roads I was just shocked at how much info wasn't coming through the wheel. Because of that I was never able to push the Z like I did the 530.