The National Highway Traffic Safety Administration said Monday it is opening new investigations into older Chrysler vehicles that stall after refueling without warning and Mazda cars with doors that fail to properly close.

NHTSA said it is investigating 192,076 2006 Chrysler 300C, Dodge Charger and Magnum cars quipped with 5.7L or 6.1L 8-cylinder HEMI engines. NHTSA said it has received 54 complaints of vehicles stalling while driving after refueling at a gas station — of those, 48 reported multiple problems. NHTSA said the complaints show an apparent increasing trend, with more than 50 percent received within the past eight months.