Ethanol is liquid at room temperature, and a 5-gallon tank weighs about one pound. In contrast a similar compressed hydrogen tank would weigh upwards of one metric tonne, due to the pathetic 11 wt-% hydrogen storage capacity.

So whether ethanol fuel cells produce carbon dioxide or not, which is irrelevant because it is reclaimed when you grow plants that produce ethanol, the storage system is featherweight, which provides a direct reduction in the weight of the car and a direct reduction in the kinetic energy of the vehicle (simple physics) and hence superior fuel economy.

Electric cars also have inherent advantages over internal combustion engine vehicles.

- wheel motors dispense with heavy drive train, transmission & axles.
- lighter chassis
- higher torque at low speed, ie towing capacity
- more interior room
- more aerodynamically-shaped vehicles possible