Model S EPA Range and MPGe don't match!

Model S EPA Range and MPGe don't match!

I'll start by stating that I admire Tesla and its technological accomplishments with the Model S.
However, something doesn't work out with the EPA numbers, and I wanted to understand it.!
Motortrend got better consumption than epa (100.7 vs 89 mpge), yet it got a significantly worse range.
That doesn't make any sense, so it got me thinking.
If you use epa 89 mpge number on 85 kwh (assuming you could really use every bit of juice in it), you get a range of 224.5 miles ((85/33.7)*89), and around 210 mile assuming 80 kwh are usable (as found out by motortrend).
If you look at the epa 265 mile range - it requires over 100 kwh of USABLE battery capacity at 89 mpge ((265/89)*33.7).

These two numbers don't match. They match much better in the epa ratings of other electric vehicles.

Any explanation?
Which one is correct - Mpge or range?

ItsNotAboutTheMoney | 28 août 2012

Mpge is wall to wheel with fudging.
Range is battery to wheel.

evanstumpges | 28 août 2012

Check out the following thread. This was discussed in great detail (check the 2nd page). There are still a few unanswered questions in my mind, but most of the EPA rating mysteries have been sorted out I think.

erezarmo | 29 août 2012

@evan, thanks for this link.
It indeed provides an explanation.
While I can understand EPA choices in both measures, I think they are wrong to provide two contradicting numbers without indicating the difference between them.

jerry3 | 29 août 2012

The EPA is a standardized test that can be repeated. It's wrong to think of it as "what you should get".

Vawlkus | 29 août 2012

@Jerry: It's INTENDED to be that. It's better used as an example withe caveat "your mileage may vary (YMMV)".

Out4aDuck | 29 août 2012

A couple of thoughts. I think the apparent descrepency in the EPA MPGe number is that they (correctly) include charging efficiency, which is about 85%. In other words, when you put 85 kWh of energy into your battery, you need to purchase 100 kWh.

Secondly, I think the EPA range estimate is remarkably accurate. I don't know what all of the hand-wringing is about. Obviously your driving style can make it better or worse.

Superliner | 29 août 2012

I wish they would abolish the whole MPGe thing alltogether. I only care about the actual miles / range capabilities of a pure BEV as configured, not some crazy formula to tell me how many miles per gallon I'd get if I were burning gas.

Just my .02

Teoatawki | 30 août 2012

+1 Superliner

The MPGe is confusing, and worse than useless. Give me something useful, like KWh / 100 mi.