The government has opened an investigation into the acceleration of some Ford Motor Co. (F) sport utility vehicles and the company's Mustang (search) sports car, officials said Tuesday.

The National Highway Traffic Safety Administration (search) said in a posting on its Web site that it was investigating reports that the engine throttle became stuck in the open position in Ford Explorers (search) and Mercury Mountaineers, causing unwanted vehicle acceleration.

The probe involves about 690,000 Explorers and Mountaineers from the 2002 model year. NHTSA said its preliminary investigation was prompted by 15 complaints and one reported crash.

The government is reviewing accelerator pedal interference with the carpet in the 2003 model year of the Mustang, Mustang convertible and Mustang GT. The review also involves the 2004 Mustang.

NHTSA said seven consumers who complained said the problem involved the position, design and installation of the carpeting. The probe involves about 20,000 Mustangs.

Ford spokeswoman Kristen Kinley said the company was working with NHTSA but that it was too early in the investigation to speculate on an outcome.