The Plymouth wing car developed for NASCAR using the Road Runner as its base was the Superbird.
Plymouth created the Superbird for the 1970 NASCAR season as a follow-up to Dodge’s 1969 Charger Daytona. Its aerodynamic nose cone, extended bodywork, pop-up headlights, and tall rear wing were designed to improve high-speed stability and reduce drag on superspeedways.
The production car was a heavily modified Plymouth Road Runner, retaining the Road Runner’s basic identity while adding specialized aerodynamic hardware. NASCAR’s homologation rules required manufacturers to sell qualifying versions to the public, which is why a road-going Superbird was offered through Plymouth dealers.
A common mix-up is confusing the Superbird with the Charger Daytona: both were Chrysler “wing cars,” but the Daytona was a Dodge based on the Charger, while the Superbird was a Plymouth based on the Road Runner. Plymouth built it for only the 1970 model year.