Your Tesla Mileage May Vary: Scientist Projects Drastically Shorter Range While Journalists Wait For Test Cars
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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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.
That's a BEAUTIFUL car. If only I could get my 6.1L Hemi with it.