In 2009, the automaker recalled 8,000 Pontiac G6 mid-size cars from the 2005 model year for a problem in which the brake lights may not come on when the pedal was pressed.
There were also problems with the brake lights turning on when the pedal was not being pressed.
NHTSA is now investigating 97 similar complaints from owners involving the model year 2004 to 2011 Chevrolet Malibu and the model year 2007 to 2009 Saturn Aura.
Safety regulators had already announced in February that they might add 550,000 cars to the recall, adding that it was investigating G6s sold from 2005 to 2009.
NHTSA says it's checking into complaints about the 2004 to 2011 Chevrolet Malibu and the 2007 to 2009 Saturn Aura.
GM says it has no reports of crashes or injuries.