Which Plymouth muscle car featured a 'beep beep' horn from the cartoon?

The Plymouth muscle car that featured a cartoon-inspired “beep beep” horn was the Road Runner.

Plymouth introduced the Road Runner for the 1968 model year as a relatively affordable, performance-focused car. Its name and graphics came from Warner Bros.’ Wile E. Coyote and the Road Runner cartoons. Chrysler paid to license the character’s likeness, while Plymouth also commissioned a special horn that imitated the Road Runner’s famous sound.

The car was based on Chrysler’s B platform, shared with models such as the Plymouth Belvedere and Satellite. It emphasized speed over luxury, with a basic interior, limited sound insulation, and a standard 383-cubic-inch V8. Buyers could also order the legendary 426 Hemi. The related Plymouth GTX was more upscale, while the Superbird was a later aerodynamic racing derivative of the Road Runner. The Barracuda was another Plymouth performance car, but it did not carry the cartoon identity or signature horn.