After licensing Steve Earle’s “The Revolution Starts Now” and getting away with it, Chevrolet might’ve been a little too cocky. From the New York Times’ Julie Bosman.

At first glance, the video looks like a typical 30-second car commercial: a shiny sport utility vehicle careers down a country road lined with sunflower fields, jaunty music playing in the background.

Then, white lettering appears on the screen: “$70 to fill up the tank, which will last less than 400 miles. Chevy Tahoe.”

The commercial is the product of one of the advertising industry’s latest trends: user-generated advertising. On March 13, Chevrolet introduced a Web site allowing visitors to take existing video clips and music, insert their own words and create a customized 30-second commercial for the 2007 Chevrolet Tahoe.

In theory, the company was hoping that visitors to its Web site would e-mail their own videos around the Web, generating interest for the Tahoe through what is known as viral marketing. By the measure of Chevrolet Tahoe videos circulating the blogosphere and the video-hosting Web sites like YouTube, that goal was achieved. But the videos that were circulated most widely like the commercial that attacked the S.U.V. for its gas mileage, may not be what Chevrolet had in mind.

Nor was the ad using a sweeping view of the Tahoe driving through a desert. “Our planet’s oil is almost gone,” it said. “You don’t need G.P.S. to see where this road leads.”

Another commercial asked: “Like this snowy wilderness? Better get your fill of it now. Then say hello to global warming.”

A spokeswoman for Chevrolet, Melisa Tezanos, said the company did not plan to shut down the anti-S.U.V. ads.

“We anticipated that there would be critical submissions,” Ms. Tezanos said. “You do turn over your brand to the public, and we knew that we were going to get some bad with the good. But it’s part of playing in this space.”