If you dig deep enough into automotive history, you’ll quickly discover that a surprising number of automakers stuffed V-12 engines inside some very unexpected vehicles. Sometimes, this was for research purposes as companies pushed the limits of technology. Others were convinced that more cylinders was the answer to the highest possible levels of performance. Then there are the outliers, cars that were built by brands or individuals responding to a very specific need that, seemingly, only a V-12 could satisfy.
Here’s a look at seven of our favorite secret V-12 prototypes and other one-off models, and our take on how they could have changed the automotive world if they’d been allowed to enter production.
1969 and 1977 Jeep Wagoneer “Jerraris”
What Was It?
When you’re a wealthy casino owner like the legendary William F. Harrah—who became synonymous with the sin bins that bore his name—there really aren’t any limits to your purchasing power. Case in point: During his lifetime, Harrah collected over a thousand vehicles and built a few of his own to boot.
Two of the most prized possessions in his collection were a pair of specially made, V-12-powered Jeep Wagoneers. As the story goes, Harrah didn’t particularly appreciate being snowed in when trying to get to his Reno casinos from Lake Tahoe and vice versa, so he sought out the four-wheel-drive capabilities of Jeep’s most comfortable ride at the time. Still, time being money to a casino magnate like Harrah, it led him to build the modified Waggies.
Why a V-12?
Enzo Ferrari is a famous curmudgeon who did things his way—regardless of how much money was shoveled in his company’s direction. Unimpressed by Harrah’s specific ask for a lifted, four-wheel-drive speed machine, Ferrari forced Harrah to take matters into his own hands by creating a bastardized model dubbed the “Jerrari,” a sport utility that grafted the entire front clip and powertrain of a Ferrari 365 GT onto a 1969 Wagoneer.
Was this the easiest way to get a V-12 engine into a Jeep ? No. Did it look super strange? Definitely. Harrah owned a Ferrari dealership at the time, so he was free to experiment with the automaker’s parts bin to his heart’s content. But the truck attracted so much attention that he eventually built a much stealthier, 1979 model that simply snagged the V-12 from a crashed 365 and installed it, sleeper-style, in a stock-looking Wagoneer.
How It Could Have Changed Everything
One thing is certain: Crossing someone like Enzo Ferrari likely made Harrah persona non grata at the Italian sports car builder for the rest of his life. In a different world, however, it’s conceivable that the two Jerraris might have pushed Ferrari in the same direction Lamborghini would eventually go with the contemporary LM002, a V-12-powered SUV that appeared roughly the same time as the Jerrari Mk 2.
The idea of two Italian 12-cylinder sport utilities duking it out for the title of world’s fastest off-roader, nearly 25 years before performance SUVs shifted the market, makes for fascinating alternate automotive history.
1971 Pontiac Firebird Pegasus V-12 “Ferraribird”
What Was It?
More than just a Mad Lib combing car badges and Greek mythology, the Pontiac Firebird Pegasus “Ferraribird” demonstrated that Enzo Ferrari wasn’t always hostile to everyone’s overtures when it came to unusual engine pairings. It probably helped that the person asking for a powerplant in this instance was legendary General Motors designer Bill Mitchell, who was a vice president at GM when he first crafted the Pegasus concept car.
Why a V-12?
Intended to combine the Pontiac Firebird’s muscle car sheetmetal with styling cues lifted from the Ferrari 250 Testa Rossa, the car’s front end was particularly Italian—and almost long enough to accommodate a 12-cylinder engine. When Mitchell asked for a V-12 from a 365 GTB/4, Enzo obliged, and it was installed along with a Ferrari-sourced instrument panel and exhaust system. Despite the stretched nose, Pontiac engineers still had to push the car’s firewall 9 inches into the cabin to make sure everything fit snug.
How It Could Have Changed Everything
In the early 1970s, the muscle car market was at a crossroads, about to be beaten down by EPA emissions regulations and a burgeoning energy crisis that pushed big-blocks to the back of the showroom. Mitchell never intended to put the Ferraribird into production, but there’s a tantalizing “what if” scenario here where Pontiac splits more dramatically from building clones of Chevrolets and instead becomes a luxury performance arm of GM, producing small-batch, American-built sports cars with licensed Italian powerplants that could skirt the edge of emissions regs through low production numbers.
With his disdain for the mass market, it’s unlikely Enzo would have gone for this proposal, and equally remote that Pontiac would have walked away from (admittedly shrinking) volume in favor of building high-dollar, bespoke sports cars. Then again, the 1970s were a strange time for the auto industry, and sometimes chaos breeds (weird) opportunity.
1989 Chevrolet Caprice V-12 Prototype
What Was It?
In the late 1980s, electronic engine controls were truly coming into their own after a hard decade of teething problems and experimentation. This was especially true in Detroit, which was on the verge of catching up to the rest of the world when it came to ECU-driven fuel economy and horsepower.
As part of its catch-up efforts, General Motors operated an extensive test fleet dedicated to perfecting very specific technologies before getting them ready for the market. This included a 1989 Chevrolet Caprice sedan test mule that was aimed at better understanding drive-by-wire throttle control, which replaced a traditional mechanical cable with a set of electronic sensors.
Why a V-12?
As it turns out, GM didn’t have any drive-by-wire tech lying around its proving grounds, so it did the next best thing: It bought a BMW 750iL, pulled the V-12 out from between its front fenders, and dropped it under the hood of its own big-boned sedan. The 750iL was the first drive-by-wire model on the market, and BMW wasn’t exactly interested in selling V-12 crate motors to the competition (however distant), which meant Chevy was on the hook for a whole 7 Series at full retail.
How It Could Have Changed Everything
Although drive-by-wire was the primary target in the V-12 Caprice’s genesis, HOT ROD’s look at the car included a tidbit from a GM employee who told them Chevrolet had indeed been considering extending the life of the full-size car’s platform by boosting its cylinder count. As we’ll see later, this wasn’t the Bowtie brand’s only brush with a V-12 drivetrain in that era, and is a 12-cylinder Caprice any crazier than Toyota’s own JDM Century V-12 sedans?
While it’s likely that any development in this era would have leaned toward a Cadillac deployment, the idea of an ultra-smooth Caprice 12-cylinder contrasted against a Ford Crown Victoria’s V-8 could have kept the vehicle alive past its mid-’90s cancellation.
1992 Chevrolet Corvette ZR-12 “Falconer”
What Was It?
The release of the Dodge Viper caught the rest of Detroit flat-footed from a supercar perspective. It’s hard to overstate the overwhelming firepower the Viper brought to bear at the time thanks to its 400-horsepower V-10 engine. Ford had no direct competitor to the car in the offing, while Chevrolet’s ZR1 Corvette (which featured similar output) was somehow Detroit’s best-kept secret, selling only a handful of examples despite its performance bonafides.
In a bit of a panic, Chevy decided to quickly churn out a concept Corvette that could best the Viper in the minds of American performance car fans. Thus, was born the Chevrolet Corvette ZR-12, also known as the “Falconer.”
Why a V-12?
It’s simple math: 12 is more than 10. That seems to have been the guiding principle behind GM’s decision to reach out to Ryan Falconer Racing about installing the company’s V-12 engine in the C4 platform. A familiar name with the racing crowd, Falconer was more accustomed to putting its aluminum V-12 in airplanes or speedboats, but with 638 horsepower and 680 lb-ft of torque on tap, it represented the kind of overwhelming firepower necessary to kill a snake.
Although it was only 100 pounds or so heavier than the stock L98 cast-iron V-8 Corvette drivetrain, the length of the motor required an 8-inch snout stretch plus the installation of through-the-fender side pipes to accommodate its enormous exhaust. If those visuals didn’t clue enthusiasts in that the ZR-12 was something special, then its non-small-block rumble definitely did.
How It Could Have Changed Everything
It’s not a stretch to say the ZR-12 could have become a production model rather than a tantalizing concept car. After all, the ZR1’s own LT5 V-8 powerplant was designed by Lotus and built by Mercury Marine, so in theory partnering with Falconer wouldn’t have been an issue if the company had been able to solve the heat management and weight balance concerns that dogged the prototype.
This would have created a super-duper Corvette that would have had truly no equal among sports cars at the time, outside of Lingenfelter- and Callaway-built customs. It would have also made the Corvette the dominant supercar of the ’90s, with only exotics like the McLaren F1 capable of keeping up.
1992 BMW M8 Prototype
What Was It?
When BMW unveiled the 8 Series in the early ’90s, it was a styling triumph but not necessarily a performance car. Its 5.0-liter V-12, shared with the 750Li, was intended to offer grand touring levels of horsepower (just under 300), doled out in smooth, respectful waves rather than adrenaline-inducing races to the redline.
This didn’t mean there weren’t plans for the 8 Series to follow in the same M-badged tire tracks as the successful M3 coupe and M5 sedan. But it did require changes to be made if the vehicle was going to be taken seriously as an elite-level performance machine.
Why a V-12?
Since a V-12 was already in place, BMW decided to do its best to up the ante on the current design. Behind the scenes, a team of BMW’s M motorsports maniacs were working on a much hotter version of the engine. They pushed the motor’s displacement up a full liter, while adding a four-valve, DOHC head and individual throttle bodies. This, plus numerous other upgrades, delivered a total of 640 horsepower in a package the company called the S70.
All that extra grunt required numerous changes to the 8 Series platform, particularly regarding adding chassis stiffness, reducing weight, accommodating much larger tires, and improving engine cooling. This included going to such extremes as swapping glass for Lexan and adding B-pillars to erase the 8 Series’ hardtop design.
How It Could Have Changed Everything
Overall, the M8 version of the car was a thorough redux that could go toe to toe with any similarly sized luxury coupe of its era. The only problem was, there weren’t any true rivals to take on. Mercedes-Benz had yet to go whole-hog on a 12-cylinder SL-Class two-door of its own, while Rolls-Royce and Bentley were far more genteel with their big-bodied entries. Then there was the economic climate, which plunged into recession right around the time the car would have gone on sale, leaving BMW fans with a much less hardcore 850 CSi V-12 model.
The engineering work that had gone into the M8’s drivetrain eventually ended up serving as the basis for the engine that powered the McLaren F1. It’s fascinating to consider a world where the one-two punch of the M8 and F1 duked it out in a luxury versus track performance battle royale with the rest of the auto industry watching from the sidelines. BMW wouldn’t build an M-badged 8 Series coupe until nearly 20 years later, this time electing to go with a turbocharged V-8 rather than a 12-cylinder symphony.
2001 BMW X5 Le Mans Concept
What Was It?
Fresh off a victory at the 24 Hours of Le Mans in 1999, BMW wanted to commemorate the occasion in the most memorable way possible. With sport utility vehicles all the rage in the luxury segment at the time, but high-performance models still a novelty, it went with an absurdly overpowered version of its X5 hauler, giving it a wide-body aero package and calling it the Le Mans Concept.
Why a V-12?
Remember that hotted-up V-12 engine that was developed first for the M8 and then used as a springboard for the McLaren F1? A descendent of that same motor was found in the prototype cars that had fought to victory at Le Mans, so BMW decided to use a 6.0-liter version of the racing 12-cylinder to power its over-the-top SUV.
After cutting big holes in the bumper to make sure they could keep the monster cool, BMW tuned the V-12 for 700 horsepower, which was enough to catapult the heavy SUV to a top speed of almost 190 mph. A six-speed manual gearbox was also included in the package, and the X5 retained all-wheel drive.
How It Could Have Changed Everything
BMW was about a year and a half away from producing the 4.8is edition of the factory X5, which was built on the 4.6is as the sportiest version of the SUV. That model was limited to just over 350 horsepower, however, which left plenty of room for a 12-cylinder model at the top of the food chain.
There’s some method to this madness: The strong-selling X5 could have easily accommodated the M8’s dormant V-12 (it fit under the hood of the BMW SUV with room to spare), giving the German brand bragging rights over the Porsche Cayenne Turbo, which at that time ruled the performance sport utility roost. Alas, BMW reserved its 12-cylinder for the 7 Series only, no doubt leaving considerable sales on the table.
2002 Cadillac Cien
What Was It
The Cadillac Cien concept did much to promote Cadillac’s Art & Science design language that would come to define the brand’s styling direction for the next decade or so. This mid-engine supercar was a shot in the arm at a time when Cadillac’s prospects seemed moribund. It also helped generate excitement for the launch of the CTS sedan the following year, which gave the automaker a much-needed makeover.
Why a V-12?
Cadillac is one of the few American car companies to have produced a factory V-12 option , although many decades before the Cien hit the scene. Choosing a 12-cylinder for the supercar was a way of introducing wow factor at auto shows while also connecting with the company’s heritage. The bespoke, 7.5-liter V-12 stuffed inside the coupe also featured then-advanced direct fuel injection technology and was good for 750 horsepower—an absurd number for the era.
How It Could Have Changed Everything
Named specifically to celebrate Cadillac’s 100-year anniversary, the Cien was more than just eye candy on a rotating dais. Cadillac fully intended to prove to the world that its mojo was back by building a production model that would compete on the global supercar stage. However unlikely this might have seemed at the time, within a decade GM was knocking on Ferrari’s and Lamborghini’s doors with the Z06 and ZR1 editions of the Corvette. Surely a supercar with a $200,000 price tag could have done the same that much earlier.
Unfortunately, Cadillac ended up downsizing its dreams into the XLR, a much more sedate Corvette-based convertible (although still angularly styled). This kept Cadillac on the outside looking in when it came to the ultra-luxury world, where it would stay for the next 25 years before the Celestiq finally escaped the company’s bean counters’ clutches.
