Awakened by accident by Inspector Gadget (when the former said "Go Go Gadgetmobile"), Gadgetmobile immediately took off from the garage, hitting his head on the door. It tried repeatedly to shake him off, but he was persistent and managed to climb in the driver's seat. Seemingly having access to his memory, it poked fun at him for his attraction to Brenda, making John try finding the mute button, which was labeled.
After a long drive of tormenting each other, Gadgetmobile comes to a screeching halt so Gadget can bust some criminals. Slow at first, it decides to take things his own way and tells him to say 10-4. It pursues one outlaw while he pursues the other. Having the capabilities of carrying different disguises (as explained by Dr. Bradford earlier in the film), it camouflages as a hedge and captures one of the criminals, caging him and humorously saying he will be serving time for the next 20 years.
Inspector Gadget becomes a hero after stopping the other criminal and, some time later, complains to Gadgetmobile he is doing nothing but small jobs. Parking in front of the police station, he decides to have a talk with Chief Quimby while it waits for him.
Later, Gadgetmobile takes Gadget, Penny, and Brain on a cruise in Riverton while he still tries to figure out a clue he found earlier (SI). Thanks to Penny's brilliant eye, he spots a van saying "Scolex Industries", with Gadgetmobile saying, "Finally a detective is in the house". He puts Gadgetmobile in auto drive and drops off the inspector in front of the building housing Scolex Industries, believing he can solve the case there.
While Gadget solves the case, Gadgetmobile was about to drop off Penny and Brain home (while talking to the audience about its dirty driving and warning kids that it is a professional and not to try it at home) when he was surprised to see Brenda at Gadget's house. She immediately takes the wheel and programs it to locate him.
It is saddened to see that his partner has been "dumped" and wipes away some tears with its windshield wipers. Luckily, with a kiss from Brenda, Gadget is brought back to life despite not needing the chip, and turns on the rocket boosters pre-installed on Gadgetmobile. He travels at dangerously high speeds trying to track down Dr. Claw (while dropping off Penny and Brain at home) and once they do, he goes on top of it hood in an attempt to arrest him. It slows down and a long, chase with Scolex's limo ensues.
It witnesses Gadget being knocked off the limo by RoboGadget as it continues chasing Claw. It, unable to slow down in time, crashes into his limo (he and his minion, Sykes, already left it) and empties thousands of Skittles out of its glove compartment and air bag. Penny arrives on a bus and notices it "got the Skittles kicked out of him".
Gadgetmobile is later seen in front of Claw's building awaiting his drop and it punches him with a boxing glove into the back side and caging him along with Mad Cat. The Riverton police arrive pointing their guns at Claw, with Gadgetmobile saying "He's all yours, boys".
In the last scene of the film, Gadgetmobile spots a red Volkswagen Beetle and decides to go on a date with it as Gadget and Brenda enjoy a romantic night together with fireworks.
Taking place one year later, Gadgetmobile has undergone a paint job and is now purple and sports 3 yellow G's, one on his hood and two on the doors. Gadgetmobile is also very lazy and so is his driver Gadget, having arrested every single criminal in Riverton.