[mceachen]

I don't know who you've talked to about this, but just because it's electric and robo-driven doesn't mean they get to skip aerodynamic drag. Air resistance increases at the square of velocity. 4 miles/kWh at 55 becomes < 2 mi/kWh at 85. 100 mph and you're measuring in kWh/mile.

[kccqzy]

If you double the speed, the air resistance gets quadrupled. Power output needed for constant speed travel is octupled (P=Fv). Now you need a higher-power motor and more expensive batteries that can sustain this kind of power output. The typical electric vehicle available today can't sustain a speed of 100 mph without thermal throttling kicking in.

Sure making the electric motor more powerful isn't that big of a problem: just look at electric trains. But making the batteries more powerful will require significant more research.