Demoralized, Theo wanders onto a freeway to admire the traffic and wishes he was fast on the first star (which is actually an airplane light). Suddenly, he gets into a freak accident when he gets sucked into the supercharger of a drag racer, fusing his DNA with nitrous oxide. The next day, when Theo wakes up, he now possesses incredible speed and accuracy, as well as some characteristics of an actual car. Unfortunately, Theo's first attempt to show this power off ends with him crashing a Big Wheel tricycle into the garden, getting himself and Chet fired from the garden crew by their foreman.
As the siblings quarrel over Theo's problems, Chet is snatched by a crow, but is pursued and rescued by Theo at a run down strip mall called Starlight Plaza. There, they are captured by Tito, a "Dos Bros" taco truck driver, and are brought to a snail race held by him and his co-workers. Theo astounds both humans and snails alike and earns the respect of the snails, led by Whiplash, with his crew members Smoove Move, Burn, Skidmark, and White Shadow, who have skills of their own. Inspired by this extraordinary snail, Tito dreams to revive the strip mall with Theo as an attraction, and eventually with the help of the snails who manage to divert and strand a tour bus and drum up impressive business. At this success, Theo convinces Tito to enter him in Indianapolis 500 as a competitor. While Tito's brother, Angelo, still declines to support him, the neighbors agree to put up the entrance fee and accompany them to Indianapolis.
At this victory, Starlight Plaza becomes a major attraction with all the businesses becoming spectacular successes including extremely elaborate snail races with Whiplash's crew getting special propulsion aids for their shells, while Chet is content as the track referee. As for Turbo, he becomes happier discovering that his shell has healed, and with that, his superspeed has returned.