You might try using:
http://www.fueleconomy.com/
Look at the highway mileage of the various cars. For example:
25/36 - Honda Civic automatic
40/45 - Honda Civic Hybrid (automatic)
48/45 - Prius (automatic)
You might drop by the magazine rack and pickup the Consumer Reports 2008 car evaluation. However, you might also look at some of the larger hybrids. The Toyota Camry Hybrid is a nice 'boat.' There is something to be said for comfort when spending over an hour each way in a car. If you expect to deal with a lot of foul weather the Ford Escape Hybrid is also a very nice ride and recently upgraded.
Bob Wilson