I HAD MY HEATED SEATS ON FOR A TRIP TO MY MOTHER'S. WE STOPPED EVERY 2 TO 3 HOURS FOR GAS AND BREAKS. 12 HOURS INTO THE 14 HOUR TRIP I STARTED FEELING PAIN ON THE BACK OF MY LEGS. I CHECKED ON OUR NEXT BREAK AND SAW BLISTERS FORMING ON THE BACKS OF MY LEGS. BY THE TIME I HAD ARRIVED MOST OF THE BLISTERS HAD POPPED. CAR WAS IN MOTION.