 This movie was based on a series of real races started by  Brock Yates (qv) of "Car & Driver" magazine. The fifth and final  race was in 1978. Yates and Hal Needham (qv) actually entered the  ambulance seen in the film. They had a doctor on board and Yates  wife Pamela as a patient. It blew its transmission in Palm Springs,  California, and arrived in Long Beach on the back of a flatbed  truck. A lot of the other vehicles were actual entries in that race.