Okay so I got an e-mail back from a lady at the EPA. The EPA states that ‘fuel efficient vehicle’ is very subjective. That totally surprises me, and also means that the bill introduced by Senator Conrad is totally worthless.
Your question sent to fueleconomy.gov about what EPA considers to be “fuel efficient vehicles" has been forwarded to EPA. The content of Senator Conrad's recently-introduced bill has not yet been officially published, so we have not yet determined what is meant by "fuel efficient vehicle". I should also caution you that the bill was only just "introduced" and has a long way to go before it is enacted. Most bills "die" some time after they are introduced. As a term, "fuel efficient vehicle" is very subjective, and depends entirely on the context in which it's being used. Thus, EPA has no MPG estimate for a fuel efficient vehicle. If the topic you are interested in is monetary incentives for buying energy-efficient vehicles, then the tax credits that were enacted in last year's energy bill are of more use to you. The Internal Revenue Service is responsible for administering these credits. They have some information via press releases they have issued athttp://www.irs.gov/newsroom/article/0,,id=153397,00.html, and also athttp://www.irs.gov/newsroom/article/0,,id=156044,00.html andhttp://www.irs.gov/newsroom/article/0,,id=156048,00.htmlHope this information helps! Linda Hormes Environmental Protection Specialist