I TURNED RIGHT INTO A PARKING SPOT IN FRONT OF A COMMERCIAL BUIDLING. I REMEMBER SLOWING DOWN AS I APPROACHED THE PARKING SPACE. AS THE CAR SLOWED, IT SUDDENLY JERKED AND THEN ACCELERATED CAUSING IT TO GO OVER THE CONCRETE PARKING HEADER AND COLLIDE INTO BUILDING EXTERIOR AND METAL GATE. THE CAR WAS IN SLOW SPEED AS I ENTERED THE SPACE. THE SUDDEN UNEXPECTED ACCELERATION CAUGHT ME BY SURPRISED AS I COULD SEE MY FOOT WAS NOT ON THE ACCELERATOR PEDAL. BY THE TIME I COULD APPLY THE BREAKS, THE CAR HAD ALREADY HIT THE BUILDING WHICH CAUSE THE CAR TO STOP MOVING. THE DISTANCE TRAVELED WAS APPROXIMATELY 12-15 FEET.