Greg's first car is a 1956 Chevrolet Bel Air.
The convertible Greg navigates through the obstacles in the family driveway is a 1971 Plymouth Barracuda. In the years since this episode was filmed in 1972, this particular year of Barracuda convertible has become an in-demand collector's item. The performance version of this car, called the "'Cuda," with the 7.0 liter "Hemi" engine, sells for several million dollars in convertible form (there were only 11 made).
The '56 Chevy Bel Air convertible used as Greg's first car was later destroyed by explosion and fire in Mannix (1967) (A Puzzle for One (1972)), which aired on November 26, 1972. Both series were produced by Paramount.
Christopher Beaumont, who plays Greg's friend who sold him the old Chevy, appears in a total of four Brady Bunch episodes playing four different roles.