Yep, you read that right. Cadillac once took a and gave it more horsepower than one of the most sought-after sports cars on the market at that time. Let’s remember the Cadillac STS-V!

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There’s an ongoing trend at Cadillac. Every now and again, the brand puts out a wild model that you can’t believe was approved by GM’s bean-counters. Then, just like that, it disappears. That’s exactly what happened with the STS-V, which, on paper, seemed like it could be America’s answer to AMG, M, and RS.

The came out just two years after the introduction of the V performance brand at Cadillac. This was the era of the first-generation CTS-V, with Corvette LS power and a six-speed manual. The CTS-V proved to be a credible threat to the likes of the BMW M3. But to be taken seriously, Cadillac needed more Vs.

So in 2005, Cadillac shocked everyone with the introduction of one of the most expensive vehicles GM had ever offered: the Corvette-based XLR, and the .

The XLR-V had a rather interesting engine choice. Rather than go with a version of the small block V8 found in its platform-mate, the Corvette Z06, Cadillac had to be “brand exclusive.” So the automaker threw a supercharger on top of the 4.6-liter Northstar V8, resulting in an impressive-for-the-time 443 hp and 413 lb-ft of torque. But Caddy’s V division wasn’t done.

Cadillac turned its attention to the favorite luxury sedan of dads with a taste for the finer things: The STS. I’m not exaggerating: in the early 2000s showing that the average Seville/STS buyer was 58 years old. That was the second-oldest buyer in Cadillac’s lineup, and an aging customer base was a problem for GM as a whole — of the top 10 cars with the oldest average buyers on J.D. Powers’ list, seven were GM products.

So Cadillac needed a way to attract younger customers, especially those interested in German sports sedans. The timing was perfect: The STS (“Seville Touring Sedan”) had just gotten a top-to-bottom redesign for 2005, moving to the rear-drive Sigma platform shared with the CTS and the SRX crossover. And while you could get the regular STS with a 320-hp version of the Northstar engine, that wasn’t going to lure away BMW buyers.

Cadillac let its V engineers put their hands all over the new STS. It got wider tires, 255/45R-18s in the front and 275/40-19s in the rear; they were Pirelli run-flats, because the bigger wheel-and-tire package couldn’t fit a spare in the trunk. The STS-V got the same 14-inch Brembo brakes that provided the stopping power on the CTS-V. The front facia got bigger air inlets with mesh grilles, and the hood grew a power bulge to accommodate the supercharger. Out back there was a small rear spoiler along with some underbody changes that actually increased the drag coefficient by 0.01, all in the name of high-speed stability. Inside, the biggest changes were sport seats with suede inserts, and a more “luxurious” dash with burled wood trim all around.

While all the go-fast and luxurious looks were cool, the big news was under the hood. Cadillac slapped a supercharger making 12 pounds of boost on top of the Northstar V8 — a slightly smaller Northstar, in fact. A two-millimeter bore reduction (from 93 to 91 millimeters) dropped this engine down from 4.6 liters to 4.4. Along with the supercharger, a reinforced cooling system along with a low restriction intake and exhaust resulted in 469 hp, 26 more than the XLR-V, and 439 lb-ft of torque. That’s more power than from the same year, a legend among sports cars. And the Cadillac had more power than most of its sport-sedan competitors: The Audi RS 6 had 450 hp from its twin-turbo V8; the Jaguar S-Type R had only 390 hp. The only sport sedan to match the Caddy was , which had 469 hp exactly.

To handle all that new power, Cadillac engineers attached an all-new six-speed automatic and reinforced the front and rear suspension cradles. The result was a heavy (4,376 lbs) but fast American performance sedan. It could run to 60 mph in just 4.8 seconds.

Of course, none of this came cheap. Pricing started at $77,090, one of the most expensive cars in Cadillac’s lineup and at GM at the time.

The STS-V is surprisingly rare today. From 2006 until its discontinuation in ‘09, . They’re pretty cheap now if you can find one: As of this writing, for just over $13,000. And if the , despite the known problems with the Northstar engine itself, STS-Vs didn’t seem to suffer too many major engine issues.

Cadillac now produces two of the . While you may not have thought about the STS-V in quite awhile, it’s obvious that today’s Cadillac V performance line owes something to the wildness of an American sedan that packed more power than a 911 Turbo, all the way back in 2006.