or we could just build more diesel cars and convert them to run off vegetable oil....
http://www.msnbc.msn.com/id/7646412/
and
http://www.msnbc.msn.com/id/7603085/
sure, it uses diesel fuel to warm the engine, but once its up to operating temp, just flip a switch, now your running with a renewable, cleaner burning fuel that doesn't rely on foreign oil.....what a concept.
of course the price of oil would probably drop drastically if these were mass produced and many people started buying them, and that just wouldn't be good for the investors in those oil companies