So your solution to the 'problem' of Chinese plastic bags in a fancy food emporium in Manhattan is to tax the poor? I'm shocked :-)
Oil is "cheap" because it's plentiful and easy to extract, refine, and use; what's wrong with that? It's that old puritanical angle that creeps into your thinking now and again ... but sure, it begs the question of sustainability: I'm all for funding research into alternate sources of energy -- and whoever gets there first is going to make a bundle, so I'm sure the interests are aligned -- but we're sorta stuck with oil for today. Limiting access to it through arbitrary taxation seems like a lose. Why not turn that around and instead of giving tax credits to poor people, give them actual credits toward more efficient cars? The worse your car is, the better your credit is :-)
/jordan