Well… how can we come up with 6000 MPG?
Jim Woolsey (the former CIA director now with Vantage Point Ventures, a VC firm that has invested in ethanol production) came up with a scheme for making flex fuel plug-in hybrids appear wildly efficient. In his scheme, you first rig the trip length the way the plug-in Prius conversion promoters do. This gets the MPGe figure up to about 100, for his hypothetical family sedan. Then, he multiplies that figure by 6.67, because E85 is only 15% gasoline. In other words the 500 MPG figure he promotes takes into account only the 15% of the fuel running through the engine that is gasoline. The fact that, by most estimates, ethanol takes either slightly more energy to produce than is yielded, or just slightly less, is not considered at all. This “500” MPG sedan consumes as much energy as a 50 mpg car: it is simply coming from three sources, but we are accounting for just one.
The mc2 is flex-fuel too. As I mentioned in my blog, it gets 110 MPG or 11 miles per kilowatt. We’ll round those down to 100 MPG and 10 miles per kilowatt, just to make the calculations easy to do without a calculator. So suppose I pick 30 miles as my average trip length. (This is about the US average daily drive, so it seems plausible.) The mc2 can easily go 26.67 miles on battery power. The remaining 3.33 miles is under engine power, so 1/30 gallon of gas is used. That’s 900 mpg, so far. (Already three times better than the Aptera claim.) Now, I apply the Woolsey factor: 6.67 x 900 = 6003 MPG. The beauty of this reasoning is that it enables one to pick essentially any figure for marketing purposes – no engineering is required: you’ll notice my mc2 went from 100 to 900 to 6000 MPG without a single engineering change.
The thing that makes this reasoning insidious is that all these figures are not, technically, lies. My 6000 MPG figure, Woolsey’s 500 MPG figure, Aptera’s 300 MPG figure, plug-in Prius 200 MPG figures, the 525 MPG figure quoted for the Volt by a GM exec – they are all plausible if you completely ignore the energy contribution of the electricity and the ethanol, and focus only on the tiny contribution made by gasoline. Lies? Not quite. Deceptive? Sure.
If you are mathematically inclined, you can see how silly this can get. My batteries will actually last slightly longer than 26.67 miles – let’s say 29 miles. In that case, only 1 mile of my 30 mile commute is on the fuel in the tank (only 15% of which is gasoline). I’ll let you do the math. The figure you’ll get will make 6000 MPG seem like SUV mileage, by comparison.
