DETROIT U.S. safety regulators have opened an investigation into consumer complaints that model year 2006 Toyota Highlander hybrid SUVs stall while driving.
"The complaints show an apparent increasing trend, with all but one received within the past year," the U.S. National Highway Traffic Safety Administration said in a filing.
No injuries or crashes as a result of the issue have been reported, NHTSA said.
NHTSA said nearly 44,000 Highlander hybrids could be subject to the reported stalling problem under investigation.
"We're cooperating fully with NHTSA's preliminary investigation," said Brian Lyons, a spokesman for Toyota Motor Co.
NHTSA has received 32 complaints from Highlander drivers, and in 21 of them, consumers report engine stalling while the vehicle was traveling at least 40 miles per hour, NHTSA said.
A preliminary investigation is the first step in a process that could lead to a recall if regulators determine that a safety issue needs to be addressed by a manufacturer.
Earlier this month, U.S. Transportation Secretary Ray LaHood said a 10-month investigation found no glitches in the electronic throttle control system used by Toyota.
That finding cleared Toyota of any problems linked to unintended acceleration other than the two issues it had already addressed through recalls -- accelerator pedals that could become stuck, and floormats that become dangerously loose and trap the pedal.
The government investigation came after a spate of safety recalls by Toyota that began in late 2009 and now total 17 million vehicles worldwide, including more than 11 million in the United States.
(Reporting by Bernie Woodall; editing by John Wallace)