Chevrolet Volt

Gas Mileage: 93 MPGe electric, 37 mpg gas
Rental Availability: Select U.S. locations
Rental Car Companies: Hertz, Enterprise
Rental Terms: Hourly and daily

The uniqueness of the Chevy Volt is that is an electric car, but it is also a gas-powered car. As a plug-in hybrid, it has both a combustion engine and a couple of electric motors to help it move forward. With a full battery it can travel on electricity alone for 35-40 miles, and after that, if you don’t plug it in again, it will use gas and return about 37 mpg—hence the two "fuel" economy ratings above.

While this makes it more flexible for longer term car rentals than a Nissan Leaf, you’ll find that it will be much more green if you can plug it in frequently during the day—so much so that you might never even use gas at all. The Volt supports the same charging as the Leaf, so, just like with the Leaf, you’ll want to sort out charging station locations ahead of time for maximum benefit.