This movie is not to be confused with The Cannonball Run, but they are both based on the same race.
Every year, there is a cross-country car race from Los Angeles to New York, with a $100,000 winner-take-all prize. The competitors include Coy "Cannonball" Buckman (David Carradine), a former NASCAR driver, and his girlfriend Linda Maxwell (Veronica Hamel), Cade Redman, who is Cannonball's rival, and Zippo Friedman, who is Cannonball's best friend. Other racers include a team of girls driving a van, a surfer (Robert Carradine) driving a Corvette, a country music singer and his mother, who is paying Redman to drive them across the country and will split the winnings, a German driver (James Keach), who is the odds-on favorite to win the race, and a suburban dad driving a Chevy Blazer.
Before the race begins, Cannonball's brother Bennie places a large bet with the mob that Cannonball will win. He decides to sabotage some of the other racecars in order for Cannonball to win. Meanwhile, the mob is going to sabotage Cannonball so they don't have to pay out.
Throughout the race, the racers are trying to take out the other drivers, while Bennie and the mob try to make sure that Cannonball does or does not win. At one point, Cannonball tells Linda to ride with Zippo because he knows he is a target, and he wants her to be safe, even though they are both driving the same type of car (a red Trans Am). Bennie successfully blows up the German driver's car, and the driver dies in the blast. Redman kicks the singer and his mom out of the car while attempting to kill Cannonball, but he dies himself when he drives off the end of an unfinished highway ramp. The mob shoots Zippo (thinking it's Cannonball), causing a multi-car crash that kills him and seriously injures Linda.
The suburban dad crosses the finish line first, but is disqualified when it's discovered he actually put his car on a transport plane and flew from LA to New York. The girls are about to cross the finish line, and would be the winners, when their van is totaled in an accident. Cannonball crosses the finish line second, and is about to check in as the winner when he learns of the multi-car accident and Linda's injuries. He also learns that his brother killed the German driver and is in line to make a lot of money with his victory. Cannonball quits the race before checking in and leaves to find Linda. The mob chases after Bennie, and it's implied that they are going to kill him. The surfer in his Corvette, who took Linda to the hospital and assumed that it cost him the race, crosses the finish line next and checks in, making him the winner of the $100,000.