In October, the Chevrolet Volt will debut for $41,000 plus shipping, while Nissan will offer its Leaf in December for $32,780. Buyers of either will qualify for a federal tax credit of $7,500, but General Motors insists the higher-priced Volt comes with greater peace of mind.

In reality, the two cars are likely to appeal to different segments of buyers. The Volt will be able to travel 40 miles on an electric charge before switching to a gasoline engine. The Leaf is an all-electric with a range of 100 miles between charges.

According to Joel Ewanick, marketing chief at GM, however, the company's research into electric vehicles, which began in the 1990s, showed that consumers will only be willing to adopt EVs on a wide scale if they have the security of a gasoline engine as a back-up.

"Our strategy will be, 'It's more car than electric,'" Ewanick said. "They're looking for a real car. They're looking for a car that will meet their transportation needs, that gives them no anxiety.. . . You can drive it across the country without having to recharge, and our competition can't do that."

In order to facilitate wider use of the products, both companies will offer lease deals. GM will lease the Volt for $350 a month for 36 months after a $2,500 down payment. The Leaf goes for $349 a month for 36 months with $1,999 down.