Rare Rides: The 1970 Plymouth Road Runner Hemi Convertible

The late 1960s and early 1970s was a halcyon era for America. The Vietnam war was raging, the youth counterculture was at odds with their parent’s generation, the country was politically divided, and the evening news brought a new tragedy into people’s living rooms on a nightly basis. MLK. RFK. Napalmed children. The Manson Family. Altamont.

While all this social and political upheaval was happening though, the automotive landscape was experiencing a Golden Era thanks to cheap gas, lax emissions standards, and designs that were more the result of passion and art than aerodynamics and safety. There was also a horsepower war being waged amongst the American manufacturers, with no end in sight.

It’s no wonder then that folks who lived through the era, and even those like me who were born in the middle of it, are obsessed with the automotive icons of the period. We worship Ford’s Shelby Mustangs, Boss 302s, and 429s; General Motors’ GTO Judge, Camaro ZL-1, and GSX 455 Stage 1; and of course, the many legends from the House of Mopar.

One car produced by the latter firm has been enshrined in muscle car lore not only for its transcendent aesthetics, prodigious power output, and nomenclature that referenced a beloved Looney Toons cartoon character but also because of its extreme rarity when equipped with certain options.

The car I’m referencing is the 1970 Plymouth Road Runner Hemi Convertible, and in this month’s edition of Rare Rides, you’re going to have the chance to learn all about it. So let’s get on it!

The 1970 Plymouth Road Runner 426 Hemi Convertible. (Photo courtesy of favcars.com.)

The origins of the 1970 Road Runner were unusually long and convoluted for a car of its era. To trace its lineage, one must actually start by exploring the history of the Plymouth Belvedere, which began nearly twenty years earlier.

First introduced in the 1951 model year, the Plymouth Cranbrook Belvedere aimed to compete against Chevy’s Bel Air and Ford’s Victoria in the low-cost, two-door segment.

The 1951 Plymouth Cranbrook Belvedere, the ultimate ancestor of the Road Runner. (Photo courtesy of barnfinds.com.)

A pillarless hardtop, the Cranbrook Belvedere was powered by a 97 horsepower, 218 cubic-inch inline-six which offered middling performance at best. In spite of this, buyers found the car’s quality for the money appealing and made it a decent seller.

The Belvedere stepped out of the Cranbrook’s shadow in 1954, becoming a stand-alone offering in the Plymouth range. Also available in four-door, station wagon, and convertible forms, the car was bequeathed a 110 horsepower, 230 cubic inch straight-six, and Chrysler’s PowerFlite two-speed slushbox.

The 1955 Plymouth Belvedere. (Photo courtesy of thewestcoastclassics.com.)

The Belvedere was given a comprehensive update in 1955. Featuring a sleek “Forward Look” design, the second-generation was given a considerable boost in available performance with a host of V8 engines on offer, as well as the first push-button automatic ever offered in an American car.

1957 saw the release of what many consider the classic iteration of the Belvedere. Sporting tons of chrome, a bold grille, and gigantic tailfins, the car would become the top model in Plymouth’s lineup. An even larger stable of powerplants would be offered, including the 350 cubic-inch “Golden Commando” V8 engine.

The third generation Belvedere became iconic due to the film Christine. (Photo courtesy of Columbia Pictures.)

Decades later, this generation of Belvedere would become iconic thanks to author Stephen King and Hollywood director John Carpenter, who wrote the book Christine, and directed the film adaptation respectively. Although identified in the book and movie as the Fury trim variant of the Belvedere, in reality, the cars used for filming were ’58 Belvederes.

The 1962 fifth-gen was a strange design. (Photo courtesy of collectingcars.com.)

1960 and ’62 yielded two rather radical and frankly strange-looking redesigns of the Belvedere. Neither of these generations resonated with the public, so in 1963 and ’64, Plymouth refreshed the car with more conservative styling that was in keeping with the aesthetics of the period. Straight lines replaced curves, and the outrageous grilles and fender profiles gave way to more modest treatments.

These inclinations continued into the sixth generation, launched in 1965. Riding on the B-body platform, the Belvedere line was expanded, with the offerings now consisting of the Satellite, Belvedere I, and Belvedere II.

The ’65 refresh resulted in increased Belvedere sales. (Photo courtesy of P.J.’s Auto World.)

The engine roster also received a refreshing, with the 225 cubic-inch slant-6 as the entry-level powerplant, and the 273, 318, 361, 383 4-barrel, and 426 Wedge becoming the V8 options for ’65.

These sporty, new design and performance changes across the Belvedere lineup resulted in a positive reaction from the press and public and generated a considerable rise in sales.

An original ad for the 1967 Plymouth GTX. (Photo courtesy of Stellantis.)

In 1967, Plymouth further broadened the Belvedere trim line with a high-end luxury muscle car in the form of the GTX. Available as a two-door hardtop or convertible, the GTX was aggressively promoted as “The Gentleman’s Muscle Car” and was equipped for business with the 375 horsepower Super Commando 440 V8 engine and the TorqueFlite 3-speed automatic.

To firmly delineate the GTX from its less-potent stablemates, the car received unique, muscular styling cues. Add-ons such as an A833 4-speed manual transmission and front disc brakes gave buyers the ability to further boost performance.

A magnificent example of a 426 Hemi-equipped 1967 GTX. (Photo courtesy of Premier Auction Group.)

But it was the 426 Hemi option that really excited stoplight warriors across the country. Adding a healthy $550 to the car’s price, the Hemi brought a factory-rated 425 ponies and 490 lb-ft of twist to the party. This gave a Hemi-equipped GTX a 13.5-second quarter-mile at 106 mph, a full second faster than a 440 car.

The GTX, although pricey, was successful with the public, with 12,010 units sold in its first year, a high number for what was essentially a niche performance model.

Eager to capitalize on a winning formula, Plymouth gave the entire Belvedere range a facelift for 1968. The sculpted flank look of the previous generation was ditched for more svelte, Coke-bottle styling with squared-off corners, beautiful fender character lines, quad headlamps, and a more streamlined roofline borrowed from the Dodge Charger.

The Sport Satellite was a new top-of-the-line model added to the Belvedere range, while the Belvedere II was dropped in favor of a new high-performance model, the Road Runner.

The new for ’68 Plymouth Road Runner. (Photo courtesy of Mecum Auctions.)

The strategy behind the Road Runner was a clever one: strip out all of the luxury items from the GTX, but leave all the performance parts intact. In that way, muscle car buyers had two Plymouths to choose from: a pricey, high-end model, and a lighter, more basic, but mechanically identical one for a far lower price.

The Road Runner name came about as a result of product planning analyst Gordon Cherry watching cartoons with his kids. He noted the Road Runner’s ability to elude Wile E. Coyote with his agility and speed and thought the name would be a perfect way to market the idea of the new car dominating the competition.

The proposed moniker was suggested to Plymouth’s brass, who were convinced to drop their plans to call the car the Plymouth La Mancha, (after the Broadway musical, Man of La Mancha.)

A licensing deal with Warner Brothers resulted in the Road Runner name and image being used for the car. (Photo courtesy of Stellantis.)

A $50,000 licensing deal, an enormous sum of money for the day, was struck with Warner Brothers to use the name and character likeness for the car. Plymouth engineers additionally spent $10,000 modifying the Belvedere’s horn to sound like the Road Runner’s “Beep-Beep.”

For power, the Road Runner came with a modified version of the venerable 383. Engineers borrowed the cylinder heads and hydraulic lifter camshaft from the 440 Magnum/Super Commando motor. Other improvements consisted of a high-rise cast-iron intake manifold with a Carter AVS four-barrel, and a high-flow, dual exhaust system. For those seeking more oomph, the 426 Hemi was offered as the lone optional lump.

The ’68 Road Runner came standard with a modified 383. (Photo courtesy of Fast Lane Cars.)

Transmitting power to the rear was a floor-shifted A-833 four-speed with an Inland shifter and an 11-inch clutch. The A727 TorqueFlite was offered for those who preferred the car to do the shifting.

Plymouth offered two diffs for the Road Runner. An 8 3/4” 3.23:1 unit lived in the 383 in 4-speed or TorqueFlite spec, as well as the Hemi automatic. A Sure-Grip LSD was optional. The Hemi 4-speed pairing required a 9 ¾” Dana 60 packing a 3.54:1 ratio Sure-Grip, or a 4.10 ratio.

The 426 Hemi was available as an option. (Photo courtesy of Fusion Luxury Motors.)

Heavy-duty suspension was installed on all Road Runners and included heavier ball joints, torsion bars, tubular hydraulic shock absorbers, and a beefy anti-roll bar.

In keeping with other performance Mopars, the Road Runner came with heavy-duty drum brakes measuring 11 x 3” and 11 x 2.50” front and rear. Power assist was an option. Also available was a power front disc system featuring 11.04-inch rotors and four-piston calipers. The 426/TorqueFlite/Sure-Grip combination mandated the front discs.

The Road Runner came standard with steelies and “dog dish” hubcaps. (Photo courtesy of Mecum Auctions.)

The 383 Road Runner rode on 14 x 5.50” steelies shod with white or red streak F70-14 bias-ply rubber with “dog-dish” hubcaps. Hemi-powered Road Runners received 15 x 6” stamped steel wheels with F70-15 red streaks. An array of optional wheels could be chosen for both.

Externally, the 1968 Road Runner was set apart from the other cars in the Belvedere range by a power bulge hood with side-facing faux scoops and engine callouts, a new grille, and a Road Runner nameplate on the dash, doors, and trunk lid. An image of the cartoon character also appeared on the trunk. Performance hood paint and vinyl roof treatments were available.

$50,000 worth of door logos. (Photo courtesy of Volo Auto Museum.)

Inside, the luxurious trappings of the GTX were stripped out. Occupants sat on vinyl/cloth or all-vinyl bench seats. No center console was available, radios were optional, and the floors were devoid of carpeting. Buyers could build back some luxury in the form of available air conditioning, automatic speed control, and head restraints though.

Budget-minded buyers went crazy for the Road Runner upon its release, with 44,499 opting for one over only 18,940 who chose a GTX. Plymouth had a genuine hit on its hands.

The ‘Runner received a mild refresh in ’69. (Photo courtesy of Amazing Classic Cars.)

Seeking to build on the momentum, Plymouth engineers upped the ante for ’69.  Two versions of the 440 – a 375 horsepower four-barrel and the 390 horse 440 Six-Pack – were offered in addition to the 383 and Hemi. The N96 “Air Grabber” hood induction system was added to the options list, as was the Track-Pak option for Hemi 4-speed cars. Larger torsion bars were installed, and a Hurst shifter replaced the Inland unit.

Outside, the car was lightly freshened with a new grille, rear lamps, rectangular side markers, and upturned, black faux hood scoops which were painted red when the Air Grabber was present. The optional performance hood paint was replaced by dual wide stripes. Most notably, an RM27 convertible top was made available.

A Hurst shifter replaced the Inland one from ’69 on. (Photo courtesy of RK Motors.)

Inside, bucket seats and a center console were the latest selectable equipment.

Motor Trend voted the Road Runner their car of the year, and an astonishing 82,019 cars were sold in 1969, including 2,818 convertibles. Owing to the fact that the Hemi and convertible options together added nearly 50% to the price of a Road Runner, it’s not surprising that only 12 such cars were ordered.

Mopar’s bird was restyled again for 1970. (Photo courtesy of Mecum Auctions.)

1970 is considered by many to be the pinnacle model year for the Golden Era, and Plymouth did not rest on its laurels when it came to improving the Road Runner.

A highly optioned 1970 Hemi convertible. (Photo courtesy of favcars.com.)

The body was smoothed out, with restyled fenders, grille, and taillights. Non-functional side scallops were located behind the doors and options such as Rallye wheels and a rear deck wing were made available. The Air Grabber option was re-worked and now featured a vacuum-activated trapdoor whose sides were decorated with a shark mouth decal. The interior was augmented with a new gauge cluster with circular gauges.

Though still spartan, the Road Runner interior received a light refresh in 1970. (Photo courtesy of favcars.com.)

All of these changes resulted in the best-looking Road Runner ever.

In spite of this, Road Runner sales plummeted, largely because of the newly introduced 1970 Barracuda and Duster that cannibalized sales. Only 40,660 1970 ‘Runners left the factory, with just 824 of them convertibles.

1970. The best looking Road Runner of all. (Photo courtesy of favcars.com.)

Out of those ragtops, only four – yes, four – were 426 cars, making the 1970 Plymouth Road Runner Hemi convertible one of the scarcest muscle cars ever made.

Determining the value of a 1970 Hemi convertible is difficult. (Image courtesy of favcars.com.)

None of these cars has changed hands of late, making its value in today’s market an unknown. But with Hemicuda convertibles fetching $3.5 million at auction, and 440-equipped Road Runner drop-tops fetching multiple hundreds of thousands in recent years, it’s safe to say that should one come up for sale, it would easily garner seven-figure money.

Outrageous for sure, but understandable for one of Mopar’s rarest rides.

About the author

Rob Finkelman

Rob combined his two great passions of writing and cars; and began authoring columns for several Formula 1 racing websites and Street Muscle Magazine. He is an avid automotive enthusiast with a burgeoning collection of classic and muscle cars.
Read My Articles

Hot Rods and Muscle Cars in your inbox.

Build your own custom newsletter with the content you love from Street Muscle, directly to your inbox, absolutely FREE!

Free WordPress Themes

We will safeguard your e-mail and only send content you request.

Street Muscle - The Ultimate Muscle Car Magazine

We'll send you the most interesting Street Muscle articles, news, car features, and videos every week.

Street Muscle - The Ultimate Muscle Car Magazine


We will safeguard your e-mail and only send content you request.

Street Muscle - The Ultimate Muscle Car Magazine

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...

Classic Ford Performance

Drag Racing

Classic Chevy Magazine

Street Muscle - The Ultimate Muscle Car Magazine

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...

  • Classic Ford Performance
  • Drag Racing
  • Classic Chevy Magazine

Street Muscle - The Ultimate Muscle Car Magazine

Thank you for your subscription.

Thank you for your subscription.

Street Muscle - The Ultimate Muscle Car Magazine

Thank you for your subscription.

Thank you for your subscription.