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I must admit I was hoping that the hp2g Mustang might have proven to have had more up its sleeve that first appeared. "Cautiously optimistic" you could say. The more skeptical engineering side of me finally took over and I calculated it out.
Everyone's right; his 110 mpg is pure BS using only the gasoline portion of the gallon of E85 to calculate mileage. Hence the apparent failure to satisfy the X-prize requirements.
I double-checked my calculations: using 25.2 MJ/L as the energy value of E85 and the published data of Cd 0.42, A=22 ft^2, and mass 3250 lb published on the hp2g website, comping him an optimistic Crr of .006 for tires the best he could hope for (i.e. efficiency=100%) to overcome rolling and aerodynamic friction at a steady 55 mph is 149 mpg.
To achieve 110mpg at a steady 55mph he would have to exceed 84% thermal efficiency (including motor friction, drive line friction, and combustion efficiency). This is simply not possible. The maximum theoretical Otto cycle efficiency is only 64% for a very high compression ratio of 14:1. An efficient drive line would knock at least another 10% off.
hp2g: I'm glad you've already brought lawyers on board with your "team." I hope they're smart enough to straighten out your claims before you sell a product to someone. I'm sure the FTC will be watching.
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