WHILE DRIVING MY X3 AT INTERSTATE SPEEDS, I ACTIVATED THE DRIVER SIDE SEAT HEATER. APPROXIMATELY TWO TO THREE MINUTES LATER, MY UPPER LEG BEGAN FEELING VERY HOT AND IT STARTED SMELLING LIKE SOMETHING WAS BURNING. I LOWERED THE SEAT HEATER TEMPERATURE FROM THE HOTTEST SETTING TO THE LOWEST/COOLEST SETTING, AND THE TEMPERATURE REMAINED THE SAME - WAS EXTREMELY HOT. A SHORT TIME LATER, I ALSO SAW SMOKE. WHEN I WAS ABLE TO PULL OVER, I SAW A HOLE ON THE SEAT WHERE THE SEAT HEATER HAD BURNED THROUGH. IT HAD ALSO BURNED THROUGH THE COAT I WAS WEARING CREATING A HOLE. CALLED THE BMW DEALERSHIP TO SEE IF THEY WOULD REPAIR AND/OR REPLACE THE SEAT HEATER AND SEAT, AND THEY REFUSED SAYING THEY WOULD NOT PAY FOR THE REPAIR SINCE THERE WAS NOT A RECALL FOR THIS DEFECT. CALLED BMW NA AND RECEIVED A SIMILAR RESPONSE.