PULLED CAR UP TO PROPANE DISPLAY OUTSIDE OF HEB GROCERY STORE. ONCE TANKS WERE EXCHANGED, NOTICED SMOKE BILLOWING FROM ENGINE. TURNED CARE OFF, GOT OUT AND NOTICED FIRE UNDERNEATH ENGINE. STORE EMPLOYEE GOT HOOD OPEN, DOUSED FIRE. CALLED WRECKER TO TOW CAR HOME. ON DECEMBER 25, 2020 NEIGHBOR NOTICED SMOKE AND BURNING WIRE SMELL COMING FROM HOOD OF CAR. OPENED HOOD DISABLED BATTERY.