Before watching "Hot Rod", I also watched "The Devil on Wheels". Both films are low budgeted exploitation films from so-called 'Poverty Row Studios'....small outfits who filmed by renting out space at major studios...often at night. In general, these films were very quickly made, cheap and less than stellar. "The Devil on Wheels" is worse, as it was made by tiny PRC....whereas "Hot Rod" was really not terrible and that's a bit of a surprise because it's from Monogram.
Judge Langham has two sons, David and Joe. Joe is a respectable policeman and David is a teenager who is fascinated with hot rods. The judge hates hot rods and they show him in court lecturing teens about the dangers of hot rodding. Because of his hatred of these fast cars, he only lets David have a car if it's not souped up and isn't a speedster. However, the young man is soon accused of driving recklessly and causing an accident. What's next? See the film.
While few would consider "Hot Rod" a great film, it's not nearly the bad film I'd expected. Much of it is that while it isn't subtle, it isn't nearly as preachy as other cheap hot rodding films of the era and teenage driving isn't a black & white issue in the picture. The judge's son isn't a terrible kid and the problem isn't as simplistic as it was in "The Devil on Wheels" and other roadster films of the day. The acting isn't bad considering everything and the film is a decent time-passer--not some cheap exploitation pic.
By the way, look for the character 'Jack'. He was played by Tommy Bond...a guy who in his childhood years appeared in dozens of Little Rascals films. He usually played Butch the bully.