Two Decades Ago You Could Buy A Cadillac With Two Engines, But Hardly Anyone Did

In the early 20th century, Cadillac was known for its expensive and exclusive V16 models. As technology developed and engines became more refined, the luxury brand abandoned such sizeable engines, and eight cylinders would forevermore be seen as “enough.” And yet, at the turn of the millennium, it was once again possible to buy a Cadillac with sixteen cylinders, albeit at your neighborhood dealership.

In the world of automotive engineering, the convention is to build cars with one engine. If you want more power, you make the engine better or get a different one. This keeps complexity and weight down and is the generally-accepted norm. And yet, there’s something inherently tantalizing about a dual-engine setup. Beyond its mechanical charms, there’s a simpler numerical thrill. Double the engines means double the horsepower!

It was the lure of the exotic that spawned the TwinStar Eldorado. It was obscure, complicated, and entirely impractical, and it had more cylinders and more power than most anything else on the road. A conventional American luxury car was turned into a stealthy road rocket that only the knowing would spot as something special.

Double Trouble

American automakers had all kinds of wild ideas in the 2000s, from the Chrysler ME Four-Twelve to the Cadillac Sixteen. However, the executives at the Big Three were always too scared—or too reasonable—to consider building them. Ultimately, when it came to the weird and the outrageous, it was up to more daring companies to take the lead.

Indeed, it was Mosler that would come to build the first sixteen-cylinder Cadillac since World War II. What’s even more amazing is that it apparently came about almost by accident.

Mosler Automotive was first founded in 1985 as Consulier Industries, later taking on the name of its founder Warren Mosler in 1993. The company focused on building small runs of high-performance sports cars, like the Consulier GTP and the Mosler MT900. These cars made a name for themselves on tracks around the world, often appearing in top-flite endurance races across the US and Europe.

Green Hawk Drive recently featured a history of Mosler and the TwinStar.

However, Mosler didn’t limit itself to outright competition machines. Its founder enjoyed experimenting with various oddball builds, which saw a twelfth-generation Cadillac Eldorado land in the company’s shop in the 1990s. Warren Mosler believed that the front-mounted Northstar V8 drivetrain might be easily swapped into the rear of the vehicle to create a mid-engined sports car. The original plan was a simple front-to-back swap, with a single engine.

A chance meeting would change all that. Speaking to Street Muscle in 2016, former Mosler engineer Jo Barras explained that one of Mosler’s friends had visited the shop, and misunderstood the build. “Warren [Mosler] had some golf buddies in the shop while the Eldo was in process, and the guy saw it and said ‘Wow, cool, a twin engine car’ or something and Warren kind of decided to have his engineers make it happen,” explained Barras.

Swapping a whole V8 engine and subframe into the back of an Eldorado doesn’t sound easy, but Borras noted it wasn’t as difficult as all that. “The subframe GM used was, dimensionally, the right size to fit in the trunk, [and] the track was a bit narrower, so we had to make some fender flares,” Borras told Street Muscle.  “The biggest issue there was getting the ducts that fed the rear radiators to both look passable and be functional.”

The car came to be known as the TwinStar, named for its dual Northstar V8 engines. Notably, though, the twin engines weren’t matched front to back, at least not in the first example built. The front engine was a 275-horsepower Northstar as found in the base model Eldorado, while the rear engine was an uprated 300-hp Northstar as found in the higher-end ETC model. This gave the car 9.1-liters of displacement and a combined total output of 575 horsepower and 595 pound-feet of torque.

Each engine was paired with its own standard four-speed automatic, effectively giving the car a very unusual all-wheel-drive setup. Gear selection was synchronized across both transmissions, since you’d always want both in drive, reverse, or park at the same time. The Northstar V8s of the time used mechanical throttles, which made it relatively simple to hook up the accelerator pedal to both engines.

Inside, the car was largely a standard Eldorado, with air conditioning, a CD stacker, and leather seating for five. “The rich elegance of the Cadillac interior is preserved in the TwinStar,” noted Mosler’s website in 1999. “The only visible change you will notice is that a second instrument cluster and ignition control have been integrated into the dash panel.”

For those wondering, this is the interior of the Cadillac Twinstar
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Mosler neatly integrated a second instrument cluster into the dash so it was possible to keep an eye on both engines.

Car and Driver was able to drive the Mosler TwinStar Eldorado, publishing its review in July 2000. It noted the joys of firing up the second engine with a button on the dash, and of watching the twin instrument panels. “Watching the two tach needles swing on different schedules is a fascinating business, but having two identical-spec engines would probably avoid the need for this redundant gimmick,” wrote Barry Winfield. The car was noted for the unconventional driving experience created by the two unique engines:

 The rear engine has a higher redline and uses lower gear ratios, so the engines shift at different times as the car accelerates. At first, this seems weird, but it feels normal after a while, particularly since it smooths the usual interruption in thrust that occurs even in cars with automatic transmissions. With the TwinStar, while one engine shifts, the other continues to pull hard. The disparity in power fore and aft is faintly detectable and is sensed as a harder push from the rear, although it’s possible that impression is the result of the louder rear-engine exhaust.

The review noted some quirks, with Mosler’s engineers suggesting the ECU was occasionally cutting performance. This was put down to the front engine’s ECU not liking the engine being pushed up to the rev limiter by the thrust of the rear engine. Still, Car and Driver was able to coax the lengthy machine into a zero-to-60 mph sprint in just 5.0 seconds flat. The quarter mile was passed in 13.4 seconds at 108 mph. The TwinStar dominated a stock Eldorado ETC, which could only achieve 6.8 seconds and 15.2 seconds respectively. In fact, it put performance close to a contemporary BMW M5, which could do the same sprint in 4.8 seconds onto a quarter mile in 13.2.

Dual engines offered big power, but they came with a serious weight penalty. The relatively long TwinStar Eldorado weighed in at 4,780 pounds, a figure which made its acceleration all the more impressive. Car and Driver noted it “actually handles pretty well in the corners,” while a racing driver hired by the magazine stated it was “amazingly well-balanced.” It pulled a respectable 0.83 g on a skidpad test—solid, if somewhat lower than proper sports cars of the era. Fuel economy was as bad as you might think, with the magazine reporting a somewhat laughable 10 mpg.

The TwinStar was impressive enough on its own, but Mosler had bigger plans. It indicated to Car & Driver it would offer TwinStar conversions for approximately $30,000. You had to supply your own Eldorado, which retailed around $40,000 at the time, but Mosler would supply the extra engine and do all the necessary work to build your twin-engined weapon. All in all, you’d be up for $70,000, which was about the price of a contemporary 2000 BMW M5, which we’re using here as a handy comparison. For your money, you were getting two less doors and no rear trunk, but you were getting an additional 175 horsepower compared to the German offering.

Sales

Mosler created print advertisements to try and sell the TwinStar to prospective customers. Notably, the primary advert reported the vehicle as having 600 horsepower, suggesting Mosler intended to fit production examples with two of the 300-horsepower V8s from the ETC.

The advertisement has performance figures from Grassroots Motorsports magazine that eclipsed those recorded by Car & Driver, including a 4.6-second zero-to-60 mph time and a 12.7-second quarter mile. Top speed was estimated at 200 mph. It’s unclear when the advert was released, but pricing was cheaper than reported by Car & Driver, with the conversion listed as costing just $21,950 including all parts and labor. Mosler would also offer to source a used Eldorado if you didn’t have one of your own already.

Five examples of the TwinStar were eventually built and sold. According to RM Sotheby’s, one was sold to Clarence Clemons of Bruce Springsteen’s E Street Band, while also quoting rumors that another was sold to comedian Jay Leno. The three remaining examples were reportedly all sold to the same customer, who desired the vehicle for its theoretical ability to retreat under gunfire. As recounted to Street Muscle by Jo Barras:

I was on the phone, and I was telling the customer all about how it handled and how it was integrated and how nice it was to drive compared to something like a Viper or blah blah, and he cut me off.  He said “Look, that’s great.  If someone walks up to the front of my car and shoots out the radiator, can I still drive away on the rear engine?”

I kind of blinked, and Warren Mosler happened to be there next to me… and I asked him.  He said, ‘I don’t see why not.’ So I told the guy, “I don’t see why not.”

He said  “I’ll take three.”

With only five examples ever built, TwinStars rarely come up for sale. The last car to publicly trade hands was the example formerly owned by Clarence Clemons, and was sold at auction for $45,000 in March 2015. It was later listed for sale in late 2015 by Florida dealer Corvette Experience, also appearing on Bring a Trailer. An initial eBay auction only hit a high bid of $17,103, which failed to meet reserve. At the time, the dealer’s website indicated it would accept $39,900 for the obscure machine. It’s unclear what became of the car after that.

In 2021, YouTube channel Doug’s Cars was able to drive a surviving example. The video is well worth the watch to see how the dual-engine coupe actually does out on the road.

By and large, the TwinStar wasn’t able to single-handedly advance the cause for the cause of dual-engined vehicles. It had the benefit of great horsepower, but suffered the drawbacks of weight and practicality. The sheer mass of two large V8 engines would always limit its performance, and as a luxury cruiser, the TwinStar would be less desirable for the sheer fact that it has no rear luggage compartment. Beyond that, there’s something to be said for the headaches of servicing such a vehicle. The TwinStar had a total of 16 sparkplugs and four head gaskets, so those major service intervals would be an absolute headache to deal with.

Dual-engine cars really don’t make a lot of sense compared to more conventional single-engined designs. That doesn’t mean they’re not cool, just that they’re never going to earn a place in the mainstream automotive market. The Mosler TwinStar Eldorado stands as an excellent demonstration of how good a dual-engined coupe could be, and for that reason, it’s worth remembering.

Top graphic images: Corvette Experience; GM