According to EPA estimates, the Toyota Prius is the most fuel-efficient vehicle sold in the U.S. The Prius also happens to be a comfortable and practical family car.
You probably won't get the EPA-rated mileage of 60 in the city and 51 on the highway, but you probably wouldn't get the EPA-rated mileage in any other vehicle, either. (And, no, those EPA mileage ratings are not backwards.)
With production finally starting to keep up with demand, the Prius is now available without a long waiting list. Don't expect to get one for less than sticker, though.