TL*THE CONTACT OWNS A 2006 GMC ENVOY DENALI. WHILE ATTEMPTING TO DECELERATE FROM APPROXIMATELY 3-5 MPH, THE VEHICLE ACCELERATED AND STRUCK THE REAR OF ANOTHER VEHICLE. CURRENTLY, THE DEALER HAS THE VEHICLE AND IS UNABLE TO DUPLICATE THE FAILURE. THE ENGINE SIZE WAS UNKNOWN. THE CURRENT AND FAILURE MILEAGES WERE 10,266.