Debbie's Aunt Belle is under attack by rival cattle rancher Beeffinger. When Tinker is captured by one of the rustler's helicopters, Speed Buggy must scale Buzzard's Butte, and the gang must form an impromptu cattle drive to save the ranch.
Tinker, Mark, Debbie and Speedy enter one of the biggest races of the year sponsored by Mr. Taggert. While they're getting ready two evil employees in a blimp prepare to ruin the race as ordered by the chief their boss. Once the race begins the employees shoot a ray out of the blimp that makes all the cars ho backwards, once Tinker and Speedy land safety they try to find help. Then, Debbie sees a branch to help grease Speedy that turns out to be a leaver that opens a secret entrance for the chief and his employees.
Speed Buggy gets invited to participate in a race in Bulgonia. Baron Vulch inserts a sophisticated bugging device in Speed Buggy's trunk to avoid customs when flying there. He then creates a female automobile named Mata Cari whom Speed Buggy falls in love with in a plot to get the bugging device back.
Speed Buggy and the kids are forced to parachute into a lost world of giant apes, one of whom takes a fancy to Speedy. But two evil scientists plan to enslave the gorillas and take over the continent. And Speedy's the bait to catch the ape.
An odd cold snap is followed by the mysterious Madam Ice, who asks Tinker to fix her car. At her Ice Palace, Tink meets Prof. Snow. They order the mechanic to build a remote-control unit to power their Freezemobiles and freeze the world.
In Egypt, the kids meet Prof. Digby, who is pursued by an invisible villain. While Speedy and Tinker are on the racetrack, Mark and Debbie are kidnapped and taken to Rishna's hideout inside the Sphinx.
During an ocean cruise to the South American Grand Prix, the gang falls overboard and make it to a remote island. They find unusual mutant plants created by Dr. Meangreen with his assistant Krelb. Dr. Meangreen plans to steal Speed Buggy's remote to control the mutant plants and take over the world.
Speed Buggy and the gang are framed of stealing an advanced battery called the K-233 Supercell as a result of the dreaded Dr. Ohm and his assistant Panku using a replica of Speedy and robbing the armored car shipping the supercell.
Speed Buggy and the gang end up on Pleasure Island while racing in the Bayou 500. Pleasure Island is occupied by an evil ringmaster who uses a special animal-controlling calliope which he plans to use in a plot to rule the world.
Speed Buggy and the gang run into Jerick the Incredible Changing Man during the the U.S.-Mexico Cross Country Race. Jerick posses the ability to alter his size and form. He targets them for a special tape that was placed in Speed Buggy's cassette player by a scientist trying to keep it from having fall into the wrong hands.
Speed Buggy and the gang are racing at the Nawambi Speedway in Africa. Meanwhile Varzak, the evil scientist and his assistant Emil steal a museum's special diamond large enough that can power the Laser-Blazer.
Speed Buggy and the gang are in Oklahoma. There they find out that learned the entire state's oil supply has been stolen. In the course of the investigation, the gang discover an underground city full of storage tanks. They also uncover that Dr. Vesuvio plans to use the stolen oil in a plot to take over the world.
Speed Buggy and the gang come across the hidden valley of Amazonia during their participation in the Himalaya 500. The hidden valley of Amazonia is a place where women rule and men are slaves. They are introduced to Queen Sheba who uses a mind-ruling device to take control of Tinker and Mark's minds. Debbie is made an Amazonian, but when she is made to do things their way she decides the ruling women are as oppressive as any male despots. She and Speed Buggy work to break Tinker, Mark and the native men from the mind ruler.
Speed Buggy and the gang take a vacation on an island and go fishing. When a marlin pulls them out to sea, they make it to a remote island that is actually an artificial island that brings them to an underwater city run by Captain Schemo. They soon learn that Captain Schemo plans to use his submarines to rule the oceans and take over the world.