4. 2014 Toyota Prius
Miles per gallon: 51 city, 48 highway, 49.5 combined
The original-recipe Prius still has the one thing everyone wants out of its brand -- incredible mileage -- but it's all of the Prius' perks that keep buyers coming back even as the efficient car market gets increasingly crowded.
A relatively cavernous 21.6 cubic feet of cargo space that turns into 40 cubic feet with the seats down, a heads-up information display on the windshield, multimedia system with app suite, an available solar roof that powers an internal fan to cool your car's interior while you're away and an available remote air conditioning system all continue to make the Prius the eco-friendly status symbol of choice.