I remember growing up watching the CHiPs TV show and seeing the episode with an off road race. Jon and Ponch drive to the Mojave Desert to race the Funeral Mountain Off Road Race in their class 3 truck. I recently came across this YouTube clip of the scene from season 3, episode 22 along with the full episode. Enjoy!
https://www.youtube.com/watch?v=qliGapRHHlI
Interview with Larry Wilcox about racing the Frontier 500.