The Plymouth Superbird is a highly modified version of the Plymouth Road Runner with applied graphic images as well as a distinctive horn sound both referencing the popular Looney Tunes cartoon character the Road Runner.
It was the factory's 1970 stock car racing design, replacing the Dodge Charger Daytona of the previous year. It included a number of small and significant engineering alterations learned from the Daytona's season of racing.
For the one year it was available, the Plymouth Superbird had three different naturally aspirated engine choices.
The base "Super Commando" 440 cid V8 with a Carter AVS-4737-S four-barrel carburetor was the most widely used. It produced 480 lb-ft of torque and 375 horsepower with a 9.7:1 compression ratio. Out of 1,920 Plymouth Road Runner Superbirds, only 93 were equipped with the powerful 7.0-liter V8 Hemi engine.
Additionally, the Hemi engine regularly appeared to produce 550 horsepower and 5800 rpm, while being designed to produce 425 horsepower and 4500 rpm.
The NASCAR Plymouth Superbird was a heavily modified version of the Plymouth Road Runner made to perform on the race track. While Plymouth only produced the Superbird for the 1970 model year, this tuned-up vehicle made its mark on automotive history, winning many NASCAR races before new rules forced it out of the sport.