that is Not a "Roadrunner"
That is a Plymouth Superbird,1970
In 1969 Dodge had a similar car the Dodge Daytona
At the beginning of the 1969 Model year, Dodge released a special version of the Dodge Charger, known as the Charger 500. This was a specially modified Charger that featured revised bodywork so that the Charger would be competitive on the NASCAR circuits. Unfortunately for Dodge, the Charger 500 did not prove to be an overwhelming winner, but merely was competitive. It wasn't that the Charger was slow, it was that the Ford and Mercury stockers were quicker.
So in order to gain supremacy on the NASCAR circuits, a batch of even more radically modified Chargers were built- this was the Charger Daytona. Featuring the same flush mounted rear window treatment as the Charger 500 (see 1969 Charger 500), the Daytona went considerably further in the quest for better aerodynamics. The final product of extensive wind tunnel testing was a car that had no equals on the track and nothing came remotely close to it in terms of visual impact on the street. An 18 inch nose cone was attached to the front of the car, and a high mounted wing was mounted on the rear. Large Daytona lettering graced the rear quarter panels and reverse mounted front fender scoops, (for tire clearance on the race versions), concealed headlights and special windshield pillar wind deflectors completed the aerodynamic package.
Engine availability on the Daytona was either the 375 hp. 440 c.i. Magnum or the 426 c.i. Hemi, of which 70 were so equipped. In all, 503 Daytona Chargers were built.
http://aerowarriors.com/
Plymouth's attempt at NASCAR domination culminated in the production of the 1970 Plymouth SuperBird. Plymouth's '68 Road Runner was aerodynamically poor, and it became even more so when Richard Petty opted to race a Ford rather than pilot a boxy Plymouth in '69. Richard scored ten victories in his new Ford ride, including a victory in the fist race he drove it in at Riverside, California. This made it abundantly clear to Plymouth that if they wanted Petty back in a Plymouth (and they wanted the all-time winningest NASCAR driver back very badly), they would need a car which Petty felt was competitive, and thus the SuperBird was born. The Plymouth SuperBird won more races in fewer appearances that its winged brother the Daytona, bringing home eight of Plymouth's 21 victories in 1970. The Plymouth was considered a great success, although ironically, Bobby Isaac won the 1970 Grand National Championship driving a Dodge. Richard Petty finished fourth, due to a serious crash at Darlington which side-lined him for several even