http://www.fueleconomy.gov/feg/2008bestworstEPAf.htm That's with the new, post-2007 EPA fuel economy methods. Prius clocks in at 48mpg, the Honda Civic Hybrid at 40mpg, and nothing else comes even remotely close.
THe numbers from
Consumer Reports are similar, showing 44mpg for the Prius, 37mpg for the HCH, then a few small cars (along with the Camry Hybrid) all at 34mpg:
http://www.consumerreports.org/cro/cars/buyingleasing/most-fuelefficient-cars-206/index.htm