The Plymouth Road Runner is a mid-size car with a focus on performance built by Plymouth in the United States between 1968 and 1980. By 1968, some of the original muscle cars were moving away from their roots as relatively cheap, fast cars as they gained features and increased in price. Plymouth developed the Road Runner to market a lower priced, basic trim model to its upscale GTX.
Third generation (1975)
The 1975 model was based on the newly restyled, more formal-looking B-body which was now called the Fury (the former full-sized Fury being called "Gran Fury"). Like the Fury, the Road Runner could be ordered with plush interiors, a rally instrument cluster in the dash board, power seats as well as windows. The Road Runner came with a blacked-out grille and a special stripe treatment to distinguish it from the Fury, as well as a heavy-duty suspension with front and rear sway bars, and rallye 14-inch or 15-inch wheels. As before the 318 was the standard engine, but it was now just with a single exhaust and 145 hp (108 kW). The engine options were however extensive; with a two-barrel/single-exhaust 170 hp (127 kW) 360, a high-performance four-barrel/dual-exhaust (Code E58) 220 hp (164 kW) 360, and three 400 CID offerings; a two-barrel/single-exhaust 160 hp (119 kW), a four-barrel/single-exhaust 185 hp (138 kW), and a high-performance (Code E68) four-barrel/dual-exhaust/moderate cam 235 hp (175 kW) were also available. In Car and Driver magazine testing of a 1975 car with the Code E68 400 engine; 0-60 happened in 8.1 seconds, the quarter-mile times were solidly in the 16-second range, and the top observed speed was 121 mph (195 km/h). While just a shadow of the 1970 figures, this performance was at least respectable for the times. All engine choices were limited to the 3-speed Torqueflite automatic, with the E58 360 and the 400 engines being available with the 3.21 axle ratio gearing. Plymouth's most powerful engine; the 440, was restricted to police models, though it has been rumored that a few 1975 Road Runners were built (via special factory order by checking off the A38 Police Pkge option) with the 255 hp (190 kW) police spec 440, along with the police spec suspension and wider (7") rims. Only 7,183 Road Runners were built in 1975, and most (just over 50%) had the 318 engine.
Although the name of the model the Road Runner was based on changed from Belvedere to Satellite to Fury, the Road Runner remained a B-body through 1975. While the Road Runner name was planned to be on a B-body in Plymouth's published literature for the 1976 model year, the name was transferred to an optional appearance package for the all-new Volare.
Source: Wikipedia