Help with a movie from the 70's please?!

Help with a movie from the 70's please?

It is an american movie and would have to be from probably '75 on for me to remember it.
Sand dunes, dune buggies, a dumb blond tripping the trip wire which had cans attached to it. The "bad" people are chasing the innocents around int their dune buggies while the "innocent" people run about and slide down the sand dunes, generally getting sand in every orifice but not getting anywhere. There are like four people out there in the desert, and I mean desert as in all sand and dunes, not like rock formations and scrub brush. NOT The Hills have Eyes. I just watched that and it was sooo not it. I am sorry I can't remember more, but thanks for reading, and thank you double if you can help.

:-)

2 weeks ago
Mad Max and Road Warrior And Thunderdome are NOT American...

I know that movie unfortunately I don't know the name. I saw it only once when I was a small child and I think it kinda scared me because the evil people were gonna kill the others in the sand buggies. wow, I thought I dreamed that but now I know it wasn't a dream but a movie I saw when I was very young. Like Dune or something I don't know. I will have to check back to see if someone knew it.