miata

There is a movie that was made in either the late 60's or early 70's about a sheriff who wanted to stop drag racers on a connon so he would reangle the horrizontal bumpers on his patrol car so when he bumps another car from behind the other car would go off the cliff. I don't know who was in it but remember watching it once when I was a little kid on TV. I only saw it once & would love to see it again. Anyone know what I'm talking about?