Seen on TV circa 70s, a guy in muscle car travels for miles (probably between cities) on underground roads that look somewhat like parking structurews. The earth's surface is probably contaminated. There are small groups of refugees living in the same tunnels. There is a show-down with Dennis Hopper-like bad guy. I remember something about deadly slugs that can drop from the ceiling (but they can be cooked and eaten). I can't remember much more but I'd like to get a hold of a copy.

It took the Movie Forum about 2 hours to respond with name of the film. Thanks to Ask Me for trying. The answer is: Circuitry Man. I've ordered a VHS copy already.