Plymouth built roughly 41,000 Road Runners for 1970, down more than half from the year before, and only three of them were Hemi convertibles. One of those three went to Canada. This gallery captures a car from the model year when insurance underwriters, not engineers, finally decided how fast an American family could afford to go. Read on for what the Air Grabber hood was hiding and why so few buyers got to find out.
Higher insurance rates for all the high powered muscle cars in 1970 are the main reason Roadrunner sales declined by more than 50%. There were around 41,000 units produced in ’70 including 824 convertibles. Only three units of the soft top “R”code (Hemi) Roadrunner left the factory in 1970, which includes the one unit sent to Canada.
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Somewhere in Canada in 1970 there was a Plymouth Road Runner convertible with a 426 Hemi under the hood, and it was one of exactly three such cars built anywhere in the world that year. Not three sent to Canada. Three built, total, across the entire model year, with that one shipped north. Numbers like that are usually the product of a car being expensive or exotic. This one was neither. The Road Runner had been conceived from the beginning as the cheap way into serious performance, and the reason almost nobody ordered the combination that would now be worth a fortune is depressingly ordinary: by 1970, they could not afford to insure it.
A Cartoon Bird and a Serious Business Plan
The Road Runner’s original business plan, launched for 1968, was one of the cleverest pieces of product thinking Detroit produced in the entire era. Plymouth stripped a mid-size Belvedere back to essentials, deleted the comfort and trim items that inflated the price of a GTX, fitted a purpose-built 383 with better-breathing heads and a hotter cam, licensed the cartoon character and its horn sound from Warner Bros., and sold the result for a figure that undercut every other factory muscle car on the market. It worked immediately and enormously. The car was fast, it was honest about what it was, and the branding gave it a personality that no spec sheet could have bought.
The Restyle That Softened a Hard Edge
For 1970 the body was comprehensively restyled, and opinion has always been split on the result. The new car sat lower and wider, with a rounder, more sculpted body, a distinctive loop bumper treatment on some configurations, and revised side scallops. Some found it more sophisticated than the blunt, businesslike 1968 and 1969 cars. Others felt it had drifted away from the deliberately plain look that made the original concept work. Either way, the restyle arrived at precisely the wrong moment commercially, because the market it was aimed at was already collapsing underneath it.
Three Convertibles, One of Them Exported
The production figures tell that story starkly. Road Runner output fell to roughly 41,000 units for 1970, down by more than half from the previous year, with 824 of those being convertibles. The Hemi option was ordered on only a tiny fraction of the total across all body styles, with the three convertibles representing the rarest configuration of all. These are not the numbers of a car that failed on merit. They are the numbers of a car whose target buyer had been priced out of the showroom by forces entirely outside Plymouth’s control.
What the Air Grabber Actually Did
The Air Grabber hood is the detail that best captures what the car was still trying to be. Rather than a fixed scoop, it used a driver-operated flap that rose up out of the hood surface to feed cold outside air directly to the carburetor, complete with shark-teeth graphics on the sides that were visible only when it was deployed. It was functional engineering with a sense of humor attached, which is the Road Runner formula in miniature. Cold air is denser air, dense air makes more power, and Plymouth saw no reason the mechanism could not also be entertaining. It was operated from inside the car, which meant a driver could leave it closed in traffic and raise it at a stoplight purely for effect, and a great many owners did precisely that.
The Engine Ladder From 383 to Hemi
Beneath it, the engine ladder started with the 383 that had defined the car from the beginning, stepped up to the 440 with a single four-barrel, then to the 440 Six Barrel with its three two-barrel carburetors, and topped out with the 426 Hemi. The Hemi in this application ran a hot camshaft and high compression and carried a factory rating of 425 gross horsepower, with period testing recording quarter-mile times in the low-to-mid 13-second range and zero-to-sixty in well under six seconds. Cars so equipped also received a heavy-duty rear axle, a Sure-Grip limited-slip differential, and structural reinforcement to cope with the loads, none of which were free and all of which the underwriters knew about.
How Insurance Killed the Segment
That is really the whole story of 1970. Insurance companies had spent the previous few years working out how to identify a high-performance car from its VIN and its engine code, and once they could, they priced accordingly. A young buyer who could scrape together the purchase price of a Hemi Road Runner frequently discovered that the annual premium approached a meaningful fraction of the car’s cost. The rational response was to buy the 383, or to buy something else entirely, and the sales figures across every manufacturer’s performance line in 1970 and 1971 show exactly that decision being made across the country simultaneously.
The Superbird Footnote
The Superbird sits alongside all of this as a footnote worth knowing. Plymouth built its winged, nose-coned NASCAR homologation special on the 1970 Road Runner, in numbers large enough to satisfy the sanctioning body and small enough to make the cars extraordinary today. It shares its underpinnings with the cars in this gallery, which means a standard 1970 Road Runner is closer to a Superbird mechanically than most people assume. The difference is aerodynamic bodywork and about two orders of magnitude in value.
Reading a 1970 Car Before You Buy One
Anyone shopping a 1970 car should read the documentation before reading the paint. Mopar fender tags and broadcast sheets encode the engine, transmission, axle ratio, paint, and options in enough detail to verify almost any claim, and in a market where a correct 440 Six Barrel car is worth multiples of a well-presented 383 car, that verification is the entire ballgame. Check the tag, check the VIN engine code, check that the axle matches what the tag says it should be, and be honest with yourself about whether a car is a documented original or a very good recreation. Plenty of both exist. Only one of them holds its value when the next buyer brings an expert along.
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