While other automakers are cutting prices and taking advantage of the rental business, General Motors is left with an increasingly smaller share of the U.S. auto market, the Detroit News reports.

Last month, Toyota Motor Co. spent more than $5,000 per vehicle on incentives for the new Tundra pickup, its first true offering in a full-size pickup segment long dominated by the domestics.

Foreign models from Kia to Hyundai are selling more cars to daily rental companies as Detroit's automakers try to scale those sales back.

Heavy incentive spending and overselling to rental fleets tarnishes an automaker's image and cuts into resale values in the long run.

Both tactics, however, have been popular with domestic automakers to boost monthly sales numbers and keep plant lines running, even as demand in the retail market dwindles.

Already this year, GM has pared sales to daily rental companies by 96,000 vehicles. Incentive spending in June was down 10 percent from a year earlier, according to Edmunds.com.

GM will continue to practice restraint, according to the Detroit News, but will still compete in the incentive battle, especially when it comes to moving trucks and clearing out older models.