MILWAUKEE — General Motors says its money-back guarantee — key to its revival — is going so well it will extend the program into early 2010.

The automaker launched its "May the Best Car Win" campaign in September as a way to get consumers to try GM cars and trucks with minimal risk. Consumers have been leery of the Detroit company since it filed for bankruptcy protection earlier this year.

The program, which offers refunds within 31 to 60 days of purchase, was slated to last two months and end Nov. 30. But it will now last until Jan. 4, 2010.

Jay Spenchian, GM's executive director of the marketing strategy support group, told The Associated Press on Thursday that more people are considering GM's four brands — Chevrolet, Cadillac, GMC and Buick — and few vehicles have been returned.

"We're starting to see big consideration changes and opinion changes," he said.

That's what the company was hoping for when it created the campaign, which includes advertisements comparing GM vehicles to those of competitors. The nation's largest automaker needs to improve sales so it can repay billions in government loans and stay in business.

Spenchian said October's numbers appear to be up. GM on Wednesday said it is likely next week to post its first year-over-year monthly sales gain in 21 months.

Consumers have been holding off on big-ticket purchases in the recession, and even if they are spending, they've been reluctant to buy from GM, which emerged from bankruptcy protection this summer.

So GM has been airing 17 television ads for its different brands, including the Chevrolet Malibu, the Buick Lacrosse and GMC Terrain, comparing them with competitors and asking consumers to pick the best car.

Andy Norton, general director, global consumer and product research, said one ad featuring the Lacrosse tested very well and showed consumers are thinking about Buick in a more positive light. Analysts say that the Buick brand has lacked a defined niche in the market and left consumers confused.

In December, GM will take the campaign to print, comparing more of its cars in ads mainly in magazines, but also in newspapers.

Spenchian said the company also hopes to harness social media — sites like Twitter and Facebook — to show consumers real people who have switched from other brands to GM products.

"We think it's going to take awhile," he said. "We also think we have to do different things. We can't be the only one saying it."