4 - Toyota Prius
Mileage: 51 city, 48 hwy
Hybrid cars rank highly based on fuel economy, but they pay a penalty because of their heavy battery packs. Cars that use nickel-metal batteries, as the Prius does, pay a higher penalty in the rankings because their batteries contain more toxic substances than do the lithium-ion batteries used in most plug-in cars.
NEXT: 5 - Honda Civic Hybrid
Last updated February 15 2011: 3:50 PM ET
