$2.35 for regular here in SF,CA. $2.65+ Premium. California "butique blend gas", or so they say. Essentially keeps the fart low potentancy until it reaches Chicago.
About two years ago the wife and I went all over Spain, in a fairly large Renault Deisel car, and it was dirt cheap, I cant remember the price. However... One thing we noticed though, was that we did not stop much. i.e. traffic and the regular "Stop'n'go" we are used to in the States was negated by high speed rotories, or so they seemed.
So there was some fuel economy we did not expect.