DRIVING MY CAR HOME I PULLED OVER IN A TURN OUT TO MOVE SOMETHING IN THE REAR COMPARTMENT THAT WAS MAKING NOISE. THAT TOOK APPROX. 30-45 SECONDS UNTIL I WAS BACK IN THE DRIVERS SEAT. I SMELLED WHAT I THOUGHT TO BE A FOREST FIRE. IT SMELLED LIKE WOOD OR TRASH BURNING, NOT A VEHICLE SMELL OF OIL, GAS, RUBBER BURNING ETC. I THEN SAW SMOKE COMING UP THROUGH THE CARPET AND FLOOR MAT OF MY FRONT PASSENGER FLOORBOARD. THIS DIDN'T MAKE SENSE TO ME, SO I QUICKLY LOOKED AT THE INSTRUMENT PANEL WHICH HAD NO INDICATION OF ENGINE TROUBLE OR OVERHEATING. SO I IMMEDIATELY REVERSED THE CAR TO SEE IF THERE WAS VEGETATION UNDER WHERE I HAD PARKED AND THERE WAS NOT. SO I PULLED BACK INTO THE LANE STILL NOT REALIZING THAT MY CAR WAS ON FIRE. AS SOON AS I PULLED OUT AND ACCELERATED IT WAS OBVIOUS THAT MY CAR WAS ON FIRE. THANK GOD THERE WAS AN IMMEDIATE EXIT TO PULL OFF OF THE HIGHWAY. I WENT TO THE BOTTOM OF THE OFF RAMP, PUT THE CAR IN PARK, POPPED THE AUTOMATIC OPENER FOR THE REAR DOOR AND TURNED THE ENGINE OFF. LUCKILY I HAD A FIRE EXTINGUISHER. SO I READ THE DIRECTIONS VERY QUICKLY AND PULLED THE PIN. THEN I PULLED THE LATCH FOR THE HOOD COMPARTMENT AND WENT TO OPEN THE HOOD. AS I LIFTED THE HOOD I SAW FLAMES SHOOTING UP FROM BEHIND THE ENGINE ALONG THE PASSENGER COMPARTMENT FIRE WALL OF THE VEHICLE. I USED MY FIRE EXTINGUISHER TO PUT OUT THE FLAMES BUT IT RAN OUT AND THE CAR WAS STILL SMOKING AND SMOLDERING. I THEN DIALED 911 FROM MY CELL PHONE AND LUCKILY A CHP WAS ONLY A MINUTE AWAY AND C