Article I picked up on drudgereport.com about proposed tax by the mile driven rather than by the gallon. I don't believe this favors hypermilers (at least those that drive alot but maximize fuel efficiency). Instead of getting the most of out of a gallon we would actually be taxed by the mile now (of course we would still save on fuel used but the savings might be offset by miles driven). And, assuming fuel prices will balloon again at some point this tax could be painful if you drive alot of miles. Still, the less gas you use the better you are making out.
AP Interview: Transportation secretary says taxing how much we drive may replace gasoline tax -- Newsday.com