I think electric vehicles are a fantastic idea and eventually will save significant amounts of pollution but when it's a cold damp day what keeps the people inside warm and the windows demisted?
The info on fuel cells was interesting by allthecoolshortnamesweretaken and at least these would give out some heat when in use, don't know about the solid oxide types a bit on the toasty side.
I think for now we have to carry on using petrol and diesel but could be used more efficiently as in the development of High Efficiency Hybrid Cycle engines, similar to the Wankel design which combines the features of the Otto, Diesel, Rankine, and Atkinson cycles, are more efficient and produce less heat.
The hybrids using a diesel or petrol engine to provide extra power or charging on most are low tech mostly using piston engines?
Hydrogen would be a good choice of fuel if it were cheaper and they reckon there might be oceans of the stuff under the sea bed, researchers from Duke University's Nicholas School of the Environment claims to have found an abundant source of hydrogen in serpentinized rocks that form from spreading tectonic plates.
Fracking moves off shore, we don't get many earthquakes here well so far.
The US is a massive country so for long journeys I think for the foreseeable future gas guzzlers are still king!