Differences and similarities between gas-electric hybrid vehicles and electric ones

Hybrid and Electric car at a glance

The move from cars powered by gas or diesel engines to those that run on electricity will start to hit its stride this year with the introduction of the Nissan Leaf and Chevrolet Volt. Three types of vehicles are emerging as automakers look for ways to get better gas mileage or avoid gasoline completely:

GAS-ELECTRIC HYBRIDS: Have both gas and electric motors that power vehicles at the same time through a common transmission. A computer decides the most efficient use of each engine. Several automakers currently have hybrids in service. The Toyota Prius is the U.S. gas mileage champ at 51 mpg in the city. Several automakers are working on plug-in hybrids that will be able to travel solely on battery power, with the hybrid system in reserve.

EXTENDED RANGE ELECTRIC: Powered by an electric motor fueled by advanced lithium-ion batteries, but they have a small gasoline engine to generate power when the batteries are depleted. The Volt, when it arrives in showrooms in December, will be able to go 40 miles on electricity from a home outlet. Then the gas engine kicks in to generate electricity, extending the range. Other automakers have plans for similar vehicles.

FULL ELECTRIC: Have an electric motor powered by lithium-ion batteries that can be charged from a home power outlet. The Leaf, also due out in December, can go 100 miles on a single charge, but when the batteries run down, it can’t move until it’s recharged. A full charge takes at least eight hours.