Used car salesman Rudy Russo (Russell) needs money to run for State Senate, so he approaches his boss Luke (Warden). Luke agrees to front him the $10,000 he needs, but then encounters an "accident" orchestrated by his brother Roy (also played by Warden), who runs the car lot across the street. Roy is hoping to claim title to his brother's property because Roy's paying off the mayor to put the new interstate through the area. After Luke disappears, it's all out war between the competing car shops, and no nasty trick is off limits as Rudy and his gang fight to keep Roy from taking Luke's property. Then Luke's daughter shows up.
Tropes used in Used Cars include:
- Cash Lure: Rudy uses a $10 bill on a fishing line to attract a customer from across the street at a competing car dealer. When the customer is chasing the money and not looking at traffic, Hilarity Ensues.
- Chekhov's Armory: In the beginning of the film, a Mexican guy who supplies them with cars says he has a ton of them just sitting around (there has to be at least 250 in a picture he shows them). Later in the movie a driver's ed teacher, who they sold crappy cars to, is angry because now his 250 students can't learn to drive. At the end of the movie the lot is being sued for false advertisement (due to the bad guy messing with an ad to say they have a mile of cars then paying off "experts" to say it wasn't tampered with). A mile of cars is said to be about 250 cars and if they don't have that many at the lot when the judge comes by to see they lose. Remember how the Mexican had at least 250 cars and how the teacher had 250 students?
- Handcuffed Briefcase: Rudy is in the process of buying his way into state government and gives a Corrupt Corporate Executive a bribe in a briefcase, which the executive handcuffs to himself while they're both sitting in a limo. When Rudy decides to renege on the deal and use the money for (slightly) more noble purposes he grabs the briefcase and slams the car door on the chain on his way out, breaking it.
- Hanging Judge: Judge H. H. Harrison is portrayed as a hanging judge, complete with model guillotine and hangman's noose on his bench. The film's villains take a chance on using Harrison, an honest judge, simply because he's guaranteed to give the harshest sentence should he find the heroes guilty.
- Heh Heh, You Said "X": The car dealership is doing an illegal broadcast by tapping into a football game and substituting their own commercial for the video feed. One of the car dealers has a deathly fear of red painted cars, and when they cut in the commercial and the flood lights are turned on, he realizes it's not a dark blue car, but a red one, so he says, "What the fuck is this, Rudy, a red car?" One of the technicians that arranged for the illegal tap in turns to Rudy and says, "Did he say 'fuck'? That's an FCC violation!" As if what they're already doing isn't...
- Honest John's Dealership: The entire film.
- Kitschy Local Commercial: First they hijack a TV transmission of an Emergency Presidential Address to hawk their rival's cars (thus getting him into trouble). In another live commercial their model loses her dress. Later a legitimate (bad) commercial says that they have "styles" of cars but the audio is altered by people working for the rival to say "miles" instead; the lot is then sued for false advertising, since they don't have a mile of cars.
- Of Corpse He's Alive: Luke is purposely given a fatal heart attack during an extreme test drive. The body is disposed of by propping the dead guy up in his favorite vintage car, setting the car in drive, and having it crash while a big sale is going on at the first dealership. The dead guy is subsequently buried in his car.
- Shoot the Television: Roy L. Fuchs smashes his TV set in a rage during President Carter's televised address, after the broadcast is hijacked by the employees of his brother Luke's used car lot, who were seeking to "advertise" their rival business on TV and destroy several cars on Roy L.'s lot in the process.
- Stripping Snag: A woman in a live TV advert gets her dress caught on a car's hood ornament and (surprise) has it completely yanked off when the hood pops open.