The Rare Factory Options That Turned Ordinary Cars Into Million-Dollar Collectibles

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With Mecum Kissimmee in full swing, it’s a good time to take a closer look at the factory options that turned performance machines into auction record holders.

When these cars were new, they weren’t conceived as future collectibles. They were production vehicles that you could walk into a dealership and order by checking boxes on a form. Many of these options were skipped simply because the average buyer didn’t feel they needed the extra performance for the added cost, and no one was thinking about how those decisions would matter decades later.

What follows isn’t an exhaustive list. It’s a cross-section of factory options and vehicles, shaped in part by what we could actually find source photos for. Some of the rarest configurations simply don’t have usable images available, so they aren’t represented here.

Decades later, those same choices are why these cars now sit at the very top of the collector market.

Among American muscle cars, few factory option combinations have proven more valuable than the pairing of 426 Hemi power and a convertible body, particularly at the end of the muscle car era.

For 1971, the final year of Hemi ’Cuda production, Plymouth built just 12 Hemi ’Cuda Convertibles. That exceptionally low production figure is the primary driver of the model’s value today.

Survivorship is extremely limited, and documentation is critical. Cars retaining their original matching-numbers 426/425 HP Hemi engines, factory drivetrains, and verified build data occupy the top tier of the collector market. Differences such as automatic versus manual transmission, axle packages, and production sequence can have a measurable impact on value among the small number of known examples.

A documented 1971 Hemi ’Cuda Convertible currently being offered at  Mecum Kissimmee 2026 illustrates how a single factory option—combining the Hemi engine with a convertible body—now places these cars among the most valuable American muscle cars ever built.

Like the other vehicles featured here, the Hemi ’Cuda Convertible’s status is not the result of racing success or aftermarket modification. Its value is defined by a factory-approved option that was technically available, rarely chosen, and never repeated.

More details.

In the late 1960s, General Motors officially limited Camaro engine displacement to 400 cubic inches. Dealers found a workaround through the Central Office Production Order (COPO) system, which allowed special-purpose vehicles to bypass standard restrictions.

Through COPO, select Camaros could be ordered with 427-cubic-inch V8s. Most received iron-block engines, but just 69 were fitted with the all-aluminum ZL1, an engine derived from Chevrolet’s Can-Am racing program. The ZL1 dramatically reduced weight while delivering immense power, making it one of the most extreme factory engine options ever installed in a street car.

That simple engine choice is what elevates documented COPO ZL1 Camaros into seven-figure territory today.

The Judge was already a bold performance and appearance package, but pairing it with a convertible body style created one of the rarest factory GTO configurations Pontiac ever offered.

Only 168 GTO Judge Convertibles were built for the 1970 model year. While no exotic engine separates these cars mechanically, the Judge package itself was a defining factory option, and combining it with an open body proved unpopular when new.

That low take rate is what drives their value today.

Dodge produced 963 Challenger R/T Convertibles in 1970. Of those, just five were ordered with the 426 Street Hemi and a four-speed manual transmission.

The Hemi was a fully factory-approved engine option, but its high cost and demanding nature discouraged most buyers, particularly in a convertible. Survivorship is exceptionally low, and the rarity of that option combination is what pushes these cars into million-dollar territory.

Built to homologate aerodynamic components for NASCAR competition, the Superbird was extreme even by muscle-car standards. Approximately 1,920 were produced, most equipped with the 440 Magnum V8.

Only roughly 135–170 were ordered with the optional 426 Hemi, a costly upgrade few buyers selected at the time. Today, that single factory engine option often separates six-figure Superbirds from seven-figure examples.

Dodge built 503 Charger Daytonas, the majority powered by the 440 Magnum. Only about 70 left the factory with the 426 Hemi, making them among the rarest American muscle cars ever produced.

The combination of radical aerodynamics and the Hemi engine created a dominant race car and one of the most valuable factory option packages of the era.

When the Mercedes-Benz 300 SL debuted in 1954, it was already revolutionary. A small number of buyers, however, were allowed to order the Leichtmetallausführung, or Light Metal Version.

This factory option replaced the standard steel body panels with aluminum and added competition-oriented components. The option carried a substantial price premium when new, and fewer than 30 alloy-bodied Gullwings were produced.

Today, documented factory alloy examples sell for millions more than standard steel-bodied cars.

The L88 was one of the most extreme factory engine options ever offered in a production Corvette. Introduced in 1967 and available through 1969, the option spanned the final year of the C2 and the early C3 generation, with the engine itself—rather than the body style—being the defining factor.

Officially rated at 430 horsepower, the aluminum-head 427-cubic-inch V-8 was intentionally underrated. Real-world output was significantly higher, but Chevrolet paired the L88 with restrictive ordering requirements that ensured only informed buyers selected it.

Choosing RPO L88 automatically bundled heavy-duty suspension and cooling components while deleting common comfort features such as a radio and heater. The result was a Corvette that prioritized performance over usability, reinforcing the engine’s competition-focused intent.

Originality and documentation are critical to value, as the L88’s purpose-built nature makes correct components and factory verification especially important. Well-documented examples, whether late-C2 or early-C3, consistently reside at the top of the Corvette market.

Like the other vehicles featured here, the L88 Corvette’s status is defined by a factory-approved option that was technically available, rarely chosen, and never intended for casual ownership. That single engine decision is what now places these cars firmly in multi-million-dollar territory.

The L89 was a factory option that spanned two Corvette generations, appearing in the final year of the C2 and the first year of the C3. Rather than being tied to a single body style, the option itself was the defining factor.

RPO L89 paired Chevrolet’s 427-cubic-inch big-block with aluminum cylinder heads, reducing weight while preserving street usability. It could be ordered with several 427 variants, making it a flexible but rarely selected performance upgrade.

In total, fewer than 850 Corvettes are believed to have been equipped with the L89 option across both model years. While not every example commands seven figures, the most original, well-documented cars—regardless of generation—have crossed the million-dollar mark at auction.

As with the other vehicles featured here, it is the factory-approved option, not the body style alone, that defines long-term value.

Offered for just one year, RPO ZR2 was a factory competition package built around the high-revving LT1 small-block V8. It bundled heavy-duty suspension, upgraded cooling, racing-focused driveline components, and deleted common comfort features.

Only 12 ZR2 Corvettes were built, making it one of the rarest factory Corvette options ever offered.

None of these cars became million-dollar collectibles by accident. In every case, the leap in value traces back to factory-approved options that were available, yet  rarely chosen.

These were not dealer modifications or one-off prototypes. They were decisions made on order forms, often dismissed as unnecessary at the time. Decades later, those same decisions define the top of the collector market.

Sometimes, the most valuable performance upgrade isn’t horsepower alone—it’s the option almost no one ordered.