Guilt-free gas guzzling.

• Author: Doherty, Brian

Cars probably pay their own way, and then some.

Even environmentalists should learn to stop worrying and love their cars, says a new study from the Reason Foundation.

Numerous studies, by sources ranging from the U.S. Department of Transportation to the World Resources Institute, claim that the price tag on the window of that car you've got your eye on doesn't tell you the half of it. Those studies accuse cars of driving off and leaving the rest of us holding the bill for anywhere from $60 billion to $700 billion every year. Those numbers represent what economists call "externalities" - costs from a transaction that get laid on people not part of the deal. But Kenneth Green of the Reason Foundation, in his study Defending Automobility, says those numbers are full of holes big enough to drive a pick-up through.

Car use definitely does impose some unpaid-for externalities, Green grants, such as the health effects of auto pollution. But those real externalities only add up to about $8 billion a year, which is more than covered by various taxes and fees directly paid by, and only by, car drivers, which add up to at least $22 billion a year.

Most of cars' supposed external costs are more fanciful, Green finds. These include cost estimates for global warming, wetland loss, land-use impact, the...