A diesel plug-in sure will be nice, imagine a vehicle with real torque and maybe 80+mpg, for even mid-size trucks, SUV's and minivans.

I think technology is there, but car company CEO's don't want to make billion $$ investment until they absolutely have to. I think the only reason Toyota dare to do this in the 90's (for hybrid), is because the chairman/CEO is a Toyota grandson, so he needn't fear losing his job if things go bad. William Ford (of Ford Motors) really had a chance to do something without too much fear, and starting a hybrid SUV (Escape) was the right choice. But Ford put nothing in improving or marketing them, so too little, and maybe too late.

As much as I hope American car companies can lead the next wave of revolution, I think Japanese (especially Toyota) will win again, because they have so much experience doing business where conditions (for fuel, pollutions, maintenance, roads, etc.) suck. Notice most news from Mideast, Africa and south America, you see only Toyota trucks (Tacoma) and Corollas running around on crappy roads, on cheapy (and direty) gas, diesel, ethanol, natural gas or whatever. You never see a GM, Ford, Benz, Honda, VW, BWM or Chrysler in these less than perfect places (except maybe an old VW bug). So how are they going to design a car for a less than perfect world?