Rare 1970 Roadrunner Convertible at Auction

A genuine 1970 Plymouth Road Runner convertible — metallic green, 383 V8, 4-speed manual — headed to no-reserve auction as part of the Rietz Mopar Collection sale in Mansfield, South Dakota. Convertible Road Runners were rare even when new, and survivors this complete rarely surface. No reserve means it sells to whoever bids highest, no matter the number. Watch to see what a car this scarce actually brings under the gavel.

Convertible muscle cars from 1970 are rare enough on their own. A 1970 Plymouth Road Runner convertible, in the right color, with the right transmission, is rare enough that most collectors go entire decades without seeing one cross an auction block. This one was headed to no-reserve sale as part of a much larger private collection being liquidated in rural South Dakota — the kind of auction where a car like this can either sell for a steal or ignite a bidding war, and there’s no way to know which until the gavel actually drops.

A Genuine 1970 Road Runner Convertible

A Genuine 1970 Road Runner Convertible
Plymouth built the Road Runner as a stripped-down, budget-focused muscle car aimed at buyers who wanted straight-line performance without paying for chrome trim and creature comforts, and the convertible body style was always the rarest configuration Plymouth offered on the platform. This example is finished in metallic green and equipped with a 383-cubic-inch V8 backed by a 4-speed manual transmission — the enthusiast’s combination, built for a driver who wanted to row their own gears rather than let a TorqueFlite automatic do the work.

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Why Convertible Road Runners Are So Hard to Find

Why Convertible Road Runners Are So Hard to Find
Muscle car buyers in 1970 overwhelmingly chose hardtops and coupes, treating convertibles as a niche option that added weight, reduced structural rigidity, and cut into the car’s straight-line performance. That buying pattern means Road Runner convertibles were a small fraction of total production even when new, and decades of attrition — rust, accidents, and simple neglect — have thinned the surviving population even further. Finding one that’s original, complete, and drivetrain-correct is genuinely difficult, which is exactly why an auction listing like this one draws attention from serious collectors the moment it’s announced.

The Rietz Mopar Collection: A Deep Well of Cars

The Rietz Mopar Collection: A Deep Well of Cars
This Road Runner was consigned as part of the Rietz Mopar Collection, a private accumulation of Mopar muscle being sold off in its entirety at a single South Dakota auction. Collections built by a single dedicated owner over years or decades tend to include cars that never made it into the usual auction circuit — vehicles bought directly from original owners, stored out of the weather, and never advertised for sale until the collection itself changes hands. That’s part of what makes an event like this one worth watching even for buyers who have no intention of bidding.

No Reserve: What That Means for Bidders

No Reserve: What That Means for Bidders
VanDerBrink Auctions listed this Road Runner as a no-reserve sale, meaning the car will sell to the highest bidder regardless of price, with no minimum the seller can quietly insist on behind the scenes. No-reserve auctions tend to attract more aggressive bidding precisely because buyers know the car is guaranteed to change hands — there’s no risk of showing up, bidding hard, and then watching the seller pull the car when the number doesn’t hit an undisclosed floor.

The 383: A Workhorse Engine With a Muscle Car Pedigree

The 383: A Workhorse Engine With a Muscle Car Pedigree
Chrysler’s 383-cubic-inch B-series V8 was one of the most common engines fitted to Road Runners across the model’s run, offering a genuine performance step up from the base six-cylinder without the cost and rarity premium of the 440 or Hemi options. It’s not the most exotic engine Plymouth ever built, but it’s a proven, well-documented platform with a large enough parts network that keeping one running and correct is far more realistic than chasing parts for a numbers-matching Hemi car.

Mansfield, South Dakota as an Auction Destination

Mansfield, South Dakota as an Auction Destination
Rural collection auctions like this one, held on-site in Mansfield rather than at a major auction house, have become a genuine draw for serious Mopar buyers willing to travel for the right car. VanDerBrink Auctions specializes in exactly this format — cataloging entire private collections and selling them where they sit, which often means better prices for buyers than a marquee televised auction, but also means doing real homework on a car’s condition before bidding, since there’s no auction-house guarantee behind the sale.

What a Sale Like This Signals for the Market

What a Sale Like This Signals for the Market
Watching what a genuine 383/4-speed convertible Road Runner actually brings at no-reserve auction gives the broader Mopar market a real data point, not a guess pulled from an online price guide. Auction results like this one get referenced by appraisers, insurers, and other sellers for years afterward, which means this single sale in Mansfield carries weight well beyond the one buyer who eventually drives the car home.

What to Check Before Bidding on a Car Like This

What to Check Before Bidding on a Car Like This
Buyers chasing a rare convertible Road Runner need to verify more than just the color and engine size before raising a paddle: matching numbers on the block, whether the 4-speed is the car’s original transmission, the condition of the convertible top mechanism and frame rails, and any history of collision or rust repair in the rear quarters. A private collection car can be exactly as advertised, or it can carry decades of undocumented work — due diligence before the auction date matters more than the excitement of finding a rare body style.

The Emotional Pull of a No-Reserve Mopar Sale

The Emotional Pull of a No-Reserve Mopar Sale
There’s a specific kind of tension that builds around a no-reserve muscle car sale that a normal listing never generates — bidders know the car will sell today, to someone, at whatever number the room settles on. For a Road Runner convertible this scarce, that tension tends to translate directly into a final price that reflects genuine scarcity rather than a seller’s optimistic asking figure, which is exactly why serious collectors watch auctions like the Rietz sale closely. A car this rare rarely needs much help finding a buyer, but it does need an honest paper trail to earn top dollar.

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