The National Highway Traffic Safety Administration (NHTSA) has expanded its probe into engine compartment fires in some General Motors cars

The National Highway Traffic Safety Administration (NHTSA) has expanded its probe into engine compartment fires in some General Motors cars with supercharged engines

The investigation began in January by studying fires in 1999-2002 Pontiac Grand Prix GTP vehicles equipped with the transverse-mounted L67 supercharged version of the GM 3800 Series II V6 engine, the NHTSA noted on its Web site this week. Now it has extended the probe to similarly equipped Buick Park Avenue, Regal and Riviera; Oldsmobile LSS; and Pontiac Bonneville models from 1999-2002. NHTSA said it is aware of 180 complaints on the vehicles that "allege non-crash-related fires originating in the engine compartment while driving or after the vehicle is parked and the ignition switched off."

The fire incident rate among the named vehicles is "significantly higher" than GM vehicles that use the non-supercharged "L36" version of the GM 3800 Series II V6, the NHTSA said. The subject fire incident rate for the supercharged 2000 Pontiac Grand Prix GTP is about 236 per 100,000 vehicles produced versus about 18 per 100,000 vehicles for the 2000 Grand Prix with the normally aspirated L36 engine, the NHTSA said.