How did they do the vehicle smash special effect?

See, this is the great thing about old school effects. They make us want to know! Now, it's all too easy...they just CGI it. This is an example of tried and true movie magic! I am sorry that I don't have an answer for you, though. I have no idea how they did the car crash scene. If I had to make a wild guess, I'd say that there was a wire across the road to stop the car immediately. I'd also guess that they weren't going as fast as it appeared in the actual crash scene and that footage was sped up carefully so as not to look sped up. I'd also say it was a trick car designed to come apart and smash up on cue when it strikes the wire and stops. But that is all guess work. It's really cool, though, however they did it!

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Whose idea was it for the word "Lisp" to have an "S" in it?

I remembered watching this movie back in 1976 when it was brand new, and over the past 40 years, that car impact scene was absolutely unforgettable. I had forgotten the name of the film even, and most of the details about it, but the image of the car folding up like an accordion against an unseen wall stayed burned into my memory. GREAT scene!