1972 Plymouth Road Runner R. Petty Apparel and Accessories by Legend Lines
The 1972 model was nearly identical to the 1971 with a few minor changes. The grille design was cleaned up, and the taillights were changed to match the new aerodynamic look of the grille. Side marker lights changed from the flush mounted side markers to the surface-mounted units. The big differences came in the cutting back of performance options for the car. The suspension, rear axle ratios, and most noticeably the engines changed, with the big-block 383 being replaced by a larger-bore (and lower performance) 400 CID version as the standard engine. The small-block 340 CID as well as the performance version of the 440 CID engine (with a 4-barrel carburetor, performance camshaft, and dual exhausts) were also available, and for the last time a 4-speed manual transmission could be paired with any of the three engines. 1972 saw new emission regulations drive power down and 1/4 mile times up. All of the engines suffered a drop in compression ratios to allow use of low-lead/no-lead gas and to meet the first round of regulations. The 1971-72 Road Runner sheet metal was used by several NASCAR racing teams for their racecars and ran well on the circuit during the 1971-74 seasons. Richard Petty won the championship both in 1971 and 1972 using the Road Runner-based cars, winning 30 races over the two seasons.