The Plymouth RoadRunner was developed as a mid-priced car and was placed between the Satellie and Belvedere model line up. It was built on the B-body platform. The RoadRunner was light and featured few amenities. This not only drove the price of the vehicle into territory that most could afford, but it gave an advantage over heavier vehicles. The front and back seats were both bench. There was no radio, no air conditioning, no cruise control, no trim, and very few color options. Most of the options available favored speed and acceleration.
Based on the heavy luxury cars in the B-body line, the Roadrunner was lighter than the compact-based ’Cuda. To make it both light and cheap, the Roadrunner had few amenities - forget about carpet, for example. Creature comforts gave way to sheer performance and cost considerations. Though the Road Runner was based on the Satellite, in 1970 it had a rallye dash and 150 mph speedometer, cost more than the Satellite, and had a lot less "frills" (depending on the year) in terms of carpet and insulation.
Plymouth payed $50,000 to Warner Brothers to use the name and cartoon likeness of their Road Runner cartoon character (as well as a "beep-beep" horn). It was a solid car and a favorite among moonshiners. It was faster than most police vehicles and due to its sturdy construction, was very reliable.
The standard engine was MOPAR’s tried and true 383 cid powerplant, which was treated to the heads, manifolds, camshafts, valve springs, and crankcase windage tray from the race ready 440 Magnum . The result: 335bhp and 425lb-ft. This was coupled with numerous other performance features including beefed up suspensions, manual transmissions, brakes, tires.
The interior was basic: a no nonsense bench seat and no carpeting - just rubber floor mats. The main attration was a base price of $2896. For those who wanted a little bit extra, there was one engine option; for $714 Plymouth would slide in a 426 Hemi. Although the Hemi clashed with the budget based principle of the Road Runner, 1/4 mile times in the low 13s needed no apologies.
A hardtop coupe and functional hood vents were added mid year during 1968. A horn that went "beep-beep" complimented the road runner decals (in gray due to time constraints) that were standard on all Road Runners. Plymouth originally estimated that it would sell 2,500 vehicles in 1968; it actually sold 45,000 copies. The 1968 Road Runner is perhaps the second most significant muscle car to the 1964 Pontiac GTO as it shifted the market back to its bang for the buck roots.
In 1969, bucket seats became available. The decals were now in color. A convertible option joined the line-up. An inexpensive engine, when compared to the Hemi, became available. This was a three-two barrel carbureted, 440 cubic-inch V8, dubbed the 440 Six Pack. Nearly 90,000 RoadRunners were sold during 1969.
The 383 engine remained the standard powerplant and a 440 CID engine with three two-barrel carburetors, known as the "440 Six Barrel"(6-BBL), was added to the lineup at mid-year to qualify the engine for the "Super Stock" drag racing class. The Six Barrel Road Runners had no wheel covers or hubcaps and a lift-off fiberglass hood. Its 440 engine produced 390 hp and 490 ft·lb of torque @ 3200 rpm, very similar numbers to the Hemi and at a lower engine speed. This meant the cheaper 440 6-BBL was nearly as fast as the 426 Hemi, at least up to highway speeds. This option, along with the economical, yet fast 383 and the outrageously fast Hemi helped propel Plymouth, and corporate sibling Dodge, to the top of the dragstrip echelon.
The Road Runner received fresh new front and rear styling for 1970. The "Six Pack" hood was dropped, but all Road Runners were now available with an optional Air Grabber Hood. This consisted of a under the dash switch which would open a power operated trap door on the hood, revealing a shark cartoon with the words "Air Grabber."
Just what you need to psyche out the competition at the stoplight. The "Air Grabber" would automatically close when the engine was turned off, to keep out the elements. The engine choices remained the same, although the Hemi went from solid to hydraulic lifters for improved durability and the standard four speed manual became an option as a strengthened three speed manual was made standard.
Due to increasing government safety regulations and emission controls, the engines began to decrease in size during the 1971 model year. Fuel prices and insurance costs also contributed to the demise of the horsepower. The wheelbase of the vehicle decreased from 116 inches to 115. A little over 14,000 examples were sold in 1971.
The standard 383cid powerplant dropped 35 bhp while the 440 engines both lost 5 bhp. The 426 Hemi stayed fast at 425 bhp. This would be the last year for the Hemi as it too would fall victim to the increased standards. Both the 2 Door Pillared Coupe and the Convertible body styles were dropped, leaving only the 2 Door Hardtop as the sole offering.
In 1972, the 440 and the Hemi were no longer offered. A 340 cubic-inch V8 engine was now available. This engine was powerful and light. Less than 7,630 Road Runners were sold during the 1972 model year.
The Road Runner received a redesigned rear bumper and side markers along with electronic ignition, 60 series tires, and a rear sway bar. The front bumper now had two vertical slots for the bumper jack and the Road Runner received a new grille. Due to increasing emission standards, the 383 V8 and the 426 Hemi were dropped. A new 400 cid V8 was introduced, rated at 255 bhp. The GTX was now available as an option on the Road Runner and came only with the 440 engine.
The 1973-74 models had more conventional squared-up styling with the front fenders slightly raised above and jutted forward of the hood. 1/4 mile times were getting close to the 16s and further away from "musclecar" status.
In 1973, a 318 cubic-inch engine was standard, producing 170 horsepower. The 440 and 400 cubic-inch engines were still offered as optional equipment. The vehicle received styling updates.
In 1974, the 360 cubic-inch engine replaced the 340 V8. The 318, two-barrel engine now produced a miserable 150 horsepower.
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"). One of the Possible engines was a high performance 400 ci engine with many common parts borrowed from the 426 hemi, it had nothing near the performance of the long gone hemi, but was at that time plymouth’s most powerful engine.
In 1976, the RoadRunner was changed to the Volare body. The standard engine was the 318 cubic-inch engine offering 150 horsepower. The 360 cubic-inch engine produced 170 horsepower. The RoadRunner package included a three-speed floor shifter, interior trim, and an improved suspension.
In 1977, an on-board engine computer, called the Lean Burn system, adorned the interior of the RoadRunner. Spoilers, stripes, and Ralley wheels, and window louvers became part of the RoadRunner package.
In 1979, a four barrel 318 was set up as an option; since many people had improved the power of their 318, reportedly without gas mileage losses, by adding a progressively opening 4-barrel, this was a good idea, but way too late. In 1979, production was just over 1000 units.
The 1980 model year was the last one for the Road Runner.