The movie was produced by James William Guercio, the same man who managed the rock group Chicago at the time. I've always admired that group. Chicago was featured on the soundtrack, and in addition, four of the members of the group got to appear in the movie as well. A short description of the movie from Wikipedia:
As I sat there, finally watching the motion picture that I could still remember so vividly from only that short promo I saw for it once back in 1973, it seemed like there was something missing. Why exactly did this motion picture stick in my mind so intensely? Why did I remember this film particularly, from only the brief trailer that must have been made for it? Then, it got to the end of the picture and the final scene unfolded - and the image that was clearly burned into my brain some 35 years ago burst from the screen in front of me. Robert Blake had stopped the van mentioned previously and, upon recognizing him, let him off with just a warning that he get a front bumper on his vehicle. As the hippie and his partner drove off, Blake realized he still had the guy's driver's license in his hand, so he remounted his trusty Harley Davidson Electra Glide and went after him to return it. As he neared the back of the Volkswagen Bus, the hippie driver's travelling companion stuck a double-barrelled shotgun out of the back window and shot Blake squarely in the chest, probably killing him instantly. The whole final scene of the movie was Blake falling off his bike and the momentum of his chase speed carrying it further down the road on it's own. This was the scene I remembered from all those years ago. Closure at last! The end of the movie played out, some 7 or 8 minutes of it, with a camera shot showing Blake dying in the middle of the road, while the vehicle carrying the camera continued on down that road looking back at the Arizona landscape and the highway and the image of Blake's body getting smaller and smaller until you couldn't see it any longer. The last thing you do see is what appears to be a vulture and it flies back toward where the body is lying and the producers of the movie freeze frame the bird when it gets just above one of the rock mountain formations seemingly growing up out of the back end of the highway. Then the credits roll and it's all over. What a powerful movie, and I'm glad to have been able to finally see it after all these years! I can highly recommend it. If you do choose to see it, buy your copy from anywhere but Wal-Mart.