I know this sounds somewhat nutty, but really I think this is the best idea I've read...
First tax all gasoline purchased then pool all that money together and return part of it as a UNIFORM tax refund and use another part to invest in alternative fuel sources. That way, those that are buying more gas are penalized.
I might favor this over higher CAFE standards (which aren't a bad idea but just haven't worked in any meaningful way), because CAFE standards seems to have too many loop holes and they aren't likely to be changed anytime soon. As this article explains:
"The way they work is to set a fuel-efficiency target that each automaker must meet on average throughout its fleet. There's one standard for cars and another, laxer standard, for "light trucks" including SUVs. As liberals like to point out, this SUV loophole doesn't make much sense. And as they're less fond of conceding, they don't make sense in part because the whole approach doesn't make sense."
http://www.prospect.org/web/page.ww?section=root&name=ViewWeb&articleId=10183