2007 GMC DENALI ROLLED BACKWARD AFTER KEY WAS REMOVED AND VEHICLE IN "PARK". CONSUMER WAS UNABLE TO STOP VEHICLE AS IT ROLLED ABOUT 100 YARDS IN LENGTH DOWN APPROXIMATELY 20 FEET. CONSUMER COULD HAVE RECEIVED MAJOR INJURIES AS VEHICLE WENT OVER A 4 FOOT WALL DURING INCIDENT AND SHE WAS UNABLE TO GET IN TO ATTEMPT TO STOP, BUT HAD TO HANG ON STEERING WHEEL IN ORDER TO NOT GET RUN OVER. *JB