Federal safety officials are investigating complaints that the Ford Freestyle crossover vehicle can lunge unexpectedly when driving at low speeds or idling.

The National Highway Traffic Safety Administration says it has received 238 complaints involving 2005 through 2007 Freestyles. Eighteen minor crashes were reported with one minor injury.

The agency said the seven-seat family haulers can lunge up to 10 feet when the driver's foot is not on the accelerator or firmly on the brakes. Stepping on the brakes firmly stops the car from moving.

Details of the investigation were posted during the weekend on NHTSA's website. The probe began May 11 and covers about 170,000 Freestyles. NHTSA will decide if a safety recall is necessary.

A Ford spokeswoman said the company is cooperating with NHTSA as it reviews the matter.

The agency said there are indications that the problem worsens when the air conditioning is on or the steering wheel is turned a lot. In both cases, the engine idle speed is increased to compensate for additional loads to run the air conditioning compressor or the power steering pump, the agency said.

The only injury reported from the problem was a knee bruise when a car collided with a pedestrian in a driveway. The person didn't need medical attention, according to NHTSA.

Incidents of brief acceleration have been reported in both forward and reverse gears, NHTSA said.

Ford renamed the Freestyle the Taurus X during the 2008 model year and stopped making the vehicle in February of 2009.

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