AFTER ~30 MIN DRIVING ON THE CAPITAL BELTWAY AROUND WASHINGTON DC, I EXISTED AT EXIT 4 ON I270 NORTH). THE ENGINE SUDDENLY EVOLVED VERY FAST WHEN I WAS BRAKING BEFORE A TRAFFIC LIGHT BETWEEN I270 RAMP AND FALLS ROAD. I FELT LIKE THE CAR JUST WANTED TO KEEP MOVING. I ENDED UP HITTING A VEHICLE IN THE FRONT THOUGH THE DAMAGES ON BOTH WERE VERY MINOR. I IMMEDIATELY TURNED OFF THE ENGINE AND PLACE IT IN PARK. AFTER A FEW MINUTES (THE OTHER DRIVER AND I EXCHANGED CONTACT INFO), I RESTARTED THE ENGINE AND THE CAR SEEMED TO WORK OK.