While the probe initially covered 177,000 model year 2011 Cruzes, the new development will effectively expand the investigation to 370,000 vehicles in total, GM spokesman Alan Adler said.
Two Cruze fires have been reported, both of which occurred while the vehicles were being driven and resulted in total losses of the cars. In both cases the driver and occupants were able to exit the vehicle without injury.
"We are conducting our own investigation and will share any findings with the government,"ť Adler stated when the investigation was initiated last month.
The NHTSA is also currently looking into 100,000 model year 2010 Jeep Wrangler vehicles following eight reports of vehicle fires.
Both safety probes could eventually lead to recalls. The NHTSA usually takes roughly six months to determine whether to upgrade an investigation into a full-blown engineering analysis, which must be performed before the government can require an automaker to conduct a recall.