Perhaps someone can develop a vegetable-shortening hybrid electric vehicle (VSHEV)? I've got a lotta Crisco on the shelf that could be put to good use, and with Crisco, your emissions will always be light, tasty, and not greasy!

(Sorry, I saw the post on temperature sensitivity and couldn't resist)

Seriously, though, I think a diesel-electric hybrid is pretty compelling. Denver converted all of their diesel buses to diesel hybrids some years back - why not cars as well?