GM claims the Volt can go for 40 miles on a fully-charged battery without the gasoline engine ever coming on - and up to 300 more miles with the small gasoline engine providing generator power. If these claims prove accurate (and we won't know until the cars are actually available about six months to a year from now) the Volt would be the most fuel-efficient car ever mass produced.
But there is a potential downside: GM reportedly will price the 2011 Volt at between $35,000 to $40,000 - comparable to the cost of an entry-luxury BMW or Mercedes-Benz. Federal tax deductions of as much as $7,500 will help make the Volt more affordable but it will still take awhile to work off the up-front costs in "down the road" fuel economy gains. Middle class buyers most interested in a high-economy car may find the Volt too expensive.
Later in 2011 or 2012, GM may also offer a similar drivetrain in the Spark ultra-compact city car, which should be priced more affordably.