U.S. Department of Energy Releases 2010 Fuel Economy Guide
Every year the U.S. Department of Energy releases a Fuel Economy Guide. The guide has some information about how to drive efficiently and fuel economy in general, but more useful in this case is that they list almost all new vehicles sold in the US with the fuel economy ration MPG for city and highway use.
It also lists the most efficient vehicles in different categories making this an excellent companion when shopping for a new car.
Download the fuel economy guide from fueleconomy.gov