AFTER EXITING A FREEWAY AND DECELERATING AND BRAKING NORMALLY, I WAITED BEHIND OTHER TRAFFIC FOR THE LIGHT TO CHANGE, WITH MY FOOT ON THE BRAKE AND THE GEAR SELECTOR IN DRIVE. SUDDENLY, THE ENGINE RPMS INCREASED SHARPLY AND MY CAR MOVED FORWARD. I WAS UNABLE TO HOLD THE CAR IN PLACE WITH THE BRAKE PEDAL. I DEPRESSED THE BRAKE SO HARD THAT I SENSED THE PULSING OF THE ABS SYSTEM. THIS WAS COMPLETELY UNEXPECTED, SO BY THE TIME I SHIFTED INTO NEUTRAL, MY CAR HAD STRUCK THE REAR OF THE ONE AHEAD. I THEN TURNED OFF THE IGNITION. NO DAMAGE WAS DONE, AND THE OTHER DRIVER AND I AGREED IT WAS A "NON-REPORTABLE" ACCIDENT. AFTER THE INCIDENT, I WAITED ABOUT 30 SECONDS AND RESTARTED THE CAR. I CONTINUED TO DRIVE HOME WITHOUT INCIDENT. MY CAR HAD OPERATED NORMALLY UNDER VARIOUS TRAFFIC CONDITIONS FOR THE PREVIOUS TWO HOURS. I WAS NOT USING THE AIR CONDITIONING AT THE TIME; I WAS RUNNING THE VENTILATOR FAN SYSTEM. IT IS HIGHLY UNLIKELY THAT I HAD DEPRESSED BOTH BRAKE AND ACCELERATOR TOGETHER, AS I HAD JUST BRAKED NORMALLY AND DID NOT MOVE MY FOOT FROM THE BRAKE PEDAL. (I CHECKED LATER TO SEE IF IT WAS EVEN POSSIBLE TO TOUCH BOTH PEDALS SIMULTANEOUSLY. I COULD NOT, WITHOUT PUTTING MY FOOT AT AN AWKWARD, ANGLED POSITION.) I ALSO CHECKED FOR A JAMMED FLOOR MAT, BUT IT WAS WELL CLEAR OF THE PEDALS. THIS UNEXPECTED ACCELERATION OCCURRED AT CA. 66,000 MI. THERE WAS ONE SUCH PREVIOUS INCIDENT, AT CA. 14,000 MI. THE MAZDA DEALER THAT REGULARLY SERVICES THE VEHICLE INSPECTED THE CAR