Toyota Prius

Gas Mileage: 50 mpg
Rental Availability: Widely available.
Rental Car Companies: Most
Rental Availability: Hourly and daily

As the most established and venerable green rental option, the Toyota Prius has remained relevant despite its age. Available in more locations than any other environmentally friendly rental vehicle, when you ask for a fuel-efficient rental the chances are good this is the vehicle you'll get. And with a combined fuel economy of 50 MPG, you’ll save some serious cash too.

Of course, there’s no plug to think about with the conventional Prius, but starting at the end of 2011 Toyota will be releasing a plug-in version of the car which will likely make its way into rental fleets as well. Much as with the Chevy Volt, the Prius Plug-in hybrid can drive on electric power from the grid for a certain number of miles after charging before reverting to using gasoline to move the car forward. Unlike the Volt, however, the Prius plug-in Hybrid can only drive about 10-14 miles on electric power stored in its batteries before turning into a rather normal Prius—albeit one with a bigger battery.

Although the Prius Plug-In isn’t yet available for consumers to purchase, car sharing pioneer, Zipcar, has worked out an agreement with Toyota to rent pre-production models hourly in three U.S. cities—Boston, San Francisco and Portland, Ore. Toyota is aiming to make the rental program a test for the vehicles under heavy everyday use. The Prius Plug-In will be available for consumers to buy starting in 2012.