Loosely picking up where Herbie Goes to Monte Carlo left off, protagonist Pete Stancheck (Stephen W. Burns) has inherited Herbie from his uncle Jim Douglas and travels to Puerto Vallarta, Mexico with his friend Davy "D.J." Johns (Charles Martin Smith) to retrieve the car. There, they befriend Paco (Joaquin Garay, III), a comically mischievous, orphaned pickpocket.
Pete and D.J. board the Sun Princess, a cruise ship, to Rio de Janeiro to enter Herbie in the Brazil Grand Primeo, while Paco follows hidden in Herbie's cargo compartment. En route they meet an anthropology student named Melissa (Elyssa Davalos) and her extravagant, eccentric aunt Louise (Cloris Leachman), who is trying to find a husband for her niece. When Herbie wreaks havoc on board, Pete pretends to court Melissa, intending that her Aunt Louise will sponsor their race.
Meanwhile, Herbie helps Paco, who has dubbed the car 'Ocho', escape captivity. When the ship's captain Blythe (Harvey Korman) has his costume party wrecked by the boy and car, he puts Herbie on trial and sentences him to be dropped into the sea. However, later on land, Herbie resurfaces from the water to reunite with Paco, who then goes into business with Herbie as a taxi.
Thereafter follow three villains (John Vernon, Alex Rocco, and Richard Jaeckel) seeking to capture an antique gold disc, and to find Paco as earlier he had pickpocketed their wallets which contained important film by threatening to use an acetylene torch to cut up Herbie; Herbie's matador part in a bullfight; romance between Aunt Louise and Captain Blythe; and bananas initially used to conceal Herbie among farm vehicles traveling to market and later used by Herbie and Paco to stop the villains escaping justice. Ultimately, the villains are captured, and the protagonists re-unite on the Sun Princess to celebrate. The group enters Herbie in an upcoming race, with Paco dressed as the driver. Davy finally asks Paco why he keeps referring to Herbie as "Ocho", since that is Spanish for eight. Paco looks at Herbie's "53" and remarks that 5+3=8. After that Pete, Davy, Aunt Louise, and Melissa have a toast hoping for Herbie to win the race with Paco giving Herbie a thumbs up.Cloris Leachman as Aunt Louise Trends
Charles Martin Smith as Davy "D.J." Johns
John Vernon as Prindle
Stephen W. Burns as Peter "Pete" Stancheck
Elyssa Davalos as Melissa
Joaquin Garay, III as Paco
Harvey Korman as Captain Blythe
Richard Jaeckel as Shepard
Alex Rocco as Quinn
Fritz Feld as Chief Steward
Vito Scotti as Armando Moccia
Herbie Goes Bananas met with negative reviews and is widely considered to be the weakest film in the Herbie franchise. Most film critics remarked that the series had run its course, with Leonard Maltin commenting that there was "one amusing scene where the VW turns matador; otherwise, strictly scrap metal." Maltin (who rated the film *½ out of ****) added that the plot dealt with its cast "encountering all sorts of 'hilarious' obstacles along the way." Phil Patton, author of the book Bug: The Strange Mutations of the World's Most Famous Automobile, observed that the Herbie franchise was "a game of diminishing returns: Herbie Goes Bananas...is filled with 'south of the border' clichés and stereotypes." On Rotten Tomatoes the film had 40% positives reviews.
The prop Herbie dropped into the ocean was never retrieved. A total of 26 VW Beetles were used, by reason of the quantity of stunts and tricks.
A paperback novelization of the film was written by Joe Claro and published by Scholastic Paperbacks in July 1980 to coincide with the film's release.
Herbie Goes Bananas was released on VHS in Late 1984 and re-released on November 6, 1985 and September 16, 1997. It was first released on DVD in Region 1 on May 4, 2004 and re-released on DVD on September 2, 2012 as part of Herbie: 4-Movie Collection with The Love Bug, Herbie Rides Again and Herbie Goes to Monte Carlo.
On June 30, 2015, Herbie Goes Bananas was released on Blu-ray Disc as a Disney Movie Club exclusive title.