The New Deal Used Car lot in Arizona is in danger of being taken over by the Roy L Fuchs car dealership across the roadway where they do business. Both dealerships are run by twin brothers, Roy L Fuchs and Luke Fuchs (both played by Jack Warden). However, Roy L's dealership is easily the more lucrative than his brother's, which deals in often junked used cars.
One of New Deal's most prominent salesmen is Ruddy Russo (Kurt Russell), a young man who never shies away from making a deal, and also is planning to run for a seat on the State Senate. Along with Ruddy, there's Jeff (Garrit Graham), a superstitious fellow, and Jim (Frank McRae), the mechanic who is easily excitable.
Recently, Luke has been having problems with his heart, much to the delight of his other brother. Roy L sends one of his mechanics over to the lot under the guise of an 'interested party,' and gets Luke to give him a test drive. However, Roy L's mechanic takes Luke on a wild ride during which Luke has a heart attack and dies.
Ruddy, Jeff, and Jim try to cover this up by burying Luke in an old Edsel in a service pit out back. When Roy L and his lawyer Sam (Joe Flaherty) show up looking for Luke, Rudy explains that Luke drove to Florida in the Edsel. Roy L believes that Ruddy is lying, but Sam explains that there's no way to disprove this claim.
Ruddy goes through with the first of several advertising stunts. Taking his camera crew out to a packed football stadium, they intend to hijack the signal for the football game to tell of their car lot. Things don't go as planned, when Jeff begins cursing on camera that the car he's standing by is red (he's superstitious about the color), and the woman they hired for the commercial ends up getting her dress ripped off on public television. The technique works, as the stunt makes newspaper headlines, and brings all sorts of people out to see the New Deal car lot.
Roy L counters this with a little stunt of his own, but in the war to win customers, Rudy does one better, and steals away Luke's customers, by setting up a gaggle of strippers to entice vehicle buyers from Roy's lot. Roy counters this with purchasing airtime to decry New Deal's business tactics.
It is then that Rudy plans to really up the stakes, and wants to try and interrupt the broadcast for the President's State of the Union address. Matters are further complicated when a woman shows up claiming to be Luke's daughter, Barbara Jane Fuchs (Deborah Harmon). Rudy attempts to get rid of her, but finds that he slowly is growing to like her.
Rudy eventually distracts her during the night of the broadcast, by taking her to dinner, and then to his place. Jeff and Jim do the commercial, with Jeff hopped up on drugs as a cowboy named 'Martial Lucky,' who shoots out and blows up several of Roy L Fuch's vehicles for the commercial.
After the broadcast, Roy L drives immediately to the New Deal lot and angrily picks a fight with Jeff for destroying his cars. As they fight, Roy L notices a picture of the service pit in an old picture, and remembers how Rudy and the others were filling it in. Roy L rushes out back, and after digging down a ways, finds the roof of his brother's old Edsel. Shortly after this, Jim contacts Rudy to come to the lot right away. Rudy does not explain to Barbara why he has to go, leaving her curious.
In the morning, the police arrive at the lot along with Roy L and his lawyer. Rudy makes up the lie that Luke came back the night before, and went to get some breakfast. During the night, Rudy, Jeff and Jim exhumed the Edsel, and have moved it out of the pit area. Jim has poured gasoline on the vehicle, and sends it off with the accelerator on. As everyone's attention is drawn to the car, they watch as it speeds out of control towards a power transformers, that erupts in a fireball, destroying Luke's body.
Roy turns to Rudy, and assumes that since Luke is dead, the lot is now his. However, Rudy explains how Luke's daughter returned, and she's staying with him. It is just then that Barbara shows up after listening to a message on Rudy's answering machine and finding out about Luke's death. Barbara fires Rudy, Jeff and Jim.
Barbara then assumes control of her father's lot, but knows very little about advertising. Roy L gains access to the script for her commercial, and hires a man to doctor up her commercial. In place of her saying 'style of cars,' the word 'mile' is substituted for 'style,' making it as though Barbara has committed a case of false advertising.
Rudy meanwhile, is still short the money he needs to run for the senate seat. However, during a football game, Jeff's superstitious nature causes Rudy to win a bet he made on the night's football game, and the next day, he meets with the party chairmen, named Tucker (Dub Taylor). However, on their way to their destination, the car passes by the New Deal lot, which has been closed by court order. Tucker explains that a 'concerned citizen' reported the lot after the commercial mentioned a 'mile of cars,' and that the trial is scheduled for the same day. Rudy immediately grabs back his money, and bolts from the car, heading towards the courthouse.
Rudy makes it in time for the trial to start. As Barbara is questioned if she does indeed have a mile of cars on her lot, Rudy mimes in the back of the room to lie and say 'yes.' Barbara does so, to which Roy's attorney claims he can prove she is lying. Rudy mawkishly yells from the back of the room, "Why don't you see for yourself, Judge?" This buys Barbara some time, as the Judge decides to come by the car lot the next day.
After the trial, Rudy uses all his campaign funds to purchase over 250 cars from a person he knows. Using the town's driver's education class, he sets out with all 250 cars headed towards the lot.
Rudy has the drivers ramp their vehicles up to 70 mph, but hits a snag when a cop ends up hitting one of the vehicles, leaving them without a 'safety margin' for error. After the incident, Rudy sends Jim up ahead to scout for any other possible issues. Jim eventually finds a police roadblock, and Rudy has his drivers take their vehicles off road.
Meanwhile, Roy L has heard of the cars, and drives out to try and intercept Rudy. A fight breaks out between the two, leading to Rudy winning, and the cars continuing to the lot. Eventually, they arrive, and fill the lot to capacity, just as the Judge arrives.
It soon becomes apparent that Jim has not arrived. Rudy radios Jeff, who is sitting along the side of a road. Jeff explains that some water washed off the blue paint on his car...revealing it as a red Fire Chief's car...and per Jeff's stigma, he can't drive a red car! Rudy attempts to convince Jeff that there is actually 'gray primer' underneath the red paint, and tells him that he is the key to helping them keep the lot.
Jeff manages to overcome his fear, and makes it to the lot just in time to help save the lot. Roy L curses out the judge, who then decides to see Roy in court for his outburst.
The film then ends with Barbara, Rudy, Jim and Jeff presiding over their saved car lot.