What’s eligible: Any 2021-model vehicle that’s available nationwide regardless of when it was introduced or last updated.

Criteria: We consider all vehicles that reduce consumption and/or minimize the release of carbon and pollutants, regardless of fuel type. Vehicles that do so at a lower overall cost have an edge over those with steep premiums. The winner was chosen from among our favorites in five eco-friendly categories: battery-electric, plug-in hybrid, gas-electric hybrid, clean diesel and regular high-mileage gasoline.