Engineer Questions Model S Real World Range
Since launching its Model S June 22 with much fanfare, and then quietly saying in a blog post this month around 50 cars have thus far been made, Tesla has been able to say it lacks cars to give the press for a customary evaluation.
This has not stopped several major car publications from writing brief overviews based on extremely short – as short as 10-minute – stints behind the wheel with Tesla personnel near at hand. Not surprisingly, some have criticized the startup for this which has generally bucked other industry practices as well, seeking to show it has a better way to do things than major automakers following what they say is tried and true industry practice.
In any event, we think more than a 10-minute test drive would be necessary to evaluate the battery range, if not the car. After all, why couldn’t they manage to set aside a couple cars to let testers have one for the day? A weekend? This would give a tester time to find out when the battery runs out.
As it is, we know an inferential statistician who is questioning the 300 mile all-electric range Tesla says is do-able. The EPA says it is good for 265 miles. But how much lower than this might the car go if pushed some, say with extra calls for precious electric energy during spirited driving or less than a hyper-miler’s finesse?
This gentleman’s name, for the sake of discussion, we’ll call “Joe.” He has two Masters of Science degrees from two different graduate schools, and worked as an engineer at a major component maker. For a number of reasons, he does not want his actual 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 Web site 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 with 85-kwh battery 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.
“My guesstimate would be that somewhere around an hour and twenty minutes would be required for a full recharge,” says Joe, “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 four-and-a-half 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 60-kwh version of the Model S yet to be released to the public, the expected range under the less than ideal conditions drops to 114 miles, Joe deduces from Tesla data. And then you have the 40-kwh base model which could very well be in Nissan Leaf range …
Tables for the expected Model S driving range can be downloaded here. Joe also provides estimated fuel cost tables, which we did not cover here. 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 will be moot once real life driving tests are available that last longer than around 10 minutes. Until then, we we don’t know if Joe’s estimate is not the more realistic picture of what to expect.