2007 SUBURBAN VEHICLE CAME TO A STOP 25FT BEHIND SEVERAL STOPPED CARS AT A RED LIGHT. WITHOUT PROVOCATION, THE VEHICLE STRONGLY ACCELERATED/SURGED FORWARD WHILE THE BRAKES WERE ENGAGED. DRIVER CONTINUED TO ATTEMPT TO STOP THE VEHICLE BY REPEATEDLY HITTING THE BRAKE PEDAL, BUT WITH NO SUCCESS. PASSENGER IN VEHICLE REPORTED SEEING DRIVERS FOOT ON THE BRAKE. VEHICLE ACCELERATED FORWARD INTO THE BACK OF ANOTHER VEHICLE WHICH WAS THEN PUSHED INTO A THIRD. ALL THREE VEHICLES SUFFERED DAMAGE. AIRBAGS FAILED TO DEPLOY IN SUBURBAN DESPITE LEVEL OF IMPACT. VEHICLE WAS TAKEN TO CHEVROLET DEALER FOR COMPLETE DIAGNOSTIC. RESULTS INCONCLUSIVE; NO DATA ERRORS RECORDED IN COMPUTERS AND NO APPARENT MECHANICAL ATTRIBUTE COULD BE FOUND RELATING TO VEHICLE ACTION. ACTION COULD NOT BE REPEATED BY TECHNICIAN. VEHICLE RELEASED TO OWNER. NO EXPLANATION COULD BE GIVEN AS TO THIS ACTION. DEALER DID NOT FOLLOW UP OR CONTINUE INVESTIGATION. *TR