Two Decades Ago, The Fastest Buick You Could Buy Was A Rare 270 HP Front-Wheel-Drive Regal

Much of General Motors in the 2000s was in a weird place. GM brands hit home runs one after another as the 20th century wound down, with models like the Buick Grand National, GMC Typhoon, and Chevrolet 454SS going on to achieve icon status. But in the 2000s? Some of GM’s marques had become known for more sedate driving, and one of those was Buick. One car tried changing that. This is the Buick Regal GSX SLP; it was not just the fastest Buick your money could buy in 2003, but it was said to be capable of outrunning lesser (according to GM) German and Japanese sport sedans.

It must have been a ball to be a domestic car enthusiast with cash in your pocket in the 2000s. If you weren’t satisfied with what came out of one of the Big Three’s factories, in many cases you could order a hopped-up version of the car or truck that you wanted and it would be delivered through your dealership, complete with a factory warranty and 50-state emissions certification. Tuners didn’t just offer go-fast versions of cars that the Big Three refused to sell, but also sometimes brought the ideas of certain concept cars to life when the manufacturer itself did not.

One of the most prolific tuners of this era was Street Legal Performance Engineering (SLP), and the firm was happy to put its magic on everything from the Chevy Blazer and Ford Ranger to Pontiac Firebird and Chevrolet Monte Carlo. While its cars were never official factory variants, they often got their manufacturers’ blessings, which was nearly as good. SLP is still around today, and is happy to sell you parts for your Ford, Dodge, or Chevy pony car, GM truck, Chevrolet Corvette, Ford F-150, or even Chevrolet Sonic.

One of SLP’s more obscure works is what it did to the Buick Regal. In SLP’s eye, the Buick Regal GSX was the ultimate package as the supercharged V6 sedan offered German sports car performance and luxury but for the lower price of a Buick. More than that, the GSX was supposed to be a return to the fast Buicks of old.

Your Grandparents’ Sleeper

The fourth-generation Buick Regal exists in a bit of a weird place in General Motors’ history. For some, the Regal had hit its peak in the 1980s with the iconic Grand National, the Turbo-T, the T-Type, and the GNX. Back then, Buick was happy to sell you a sinister coupe that was so fast that it could outrun some modern sporty cars today, four decades later.

Buick followed it up with a hard turn in late 1987, when the Regal moved to General Motors’ W-body platform. The Regal became a front-wheel-drive car, and both of the performance models and their hot engines disappeared. The third-generation Regal spent most of its run making no more than 170 HP. That finally changed in 1996, the Regal’s final year, when it got a Buick L36 3.8-liter V6 good for 205 HP.

As MotorTrend wrote in 1997, Buick’s image had become one of a brand preferred by retirees. There wasn’t necessarily anything wrong with this, but it was a different kind of Buick than enthusiasts had known.

The fourth-generation model, which launched in 1997, finally put speed and power back on the menu – though in a form factor that enthusiasts perhaps weren’t used to. As the Chicago Tribune writes, the new Regal followed tradition and was based on the Century, which itself rode on the then-latest iteration of the GM W-body platform alongside the Pontiac Grand Prix, Oldsmobile Intrigue, Chevrolet Impala, among other models. The new W-bodies were bigger, roomier, and more comfortable.

On the outside, the Chicago Tribune notes, the metal was all-new, but still conservative. While Buick had been hard at work making bigger, more comfortable, and better-performing cars, it didn’t want to rock the boat too much in styling. The Century and the Cutlass were, as the Chicago Tribune notes, targeting buyers who cared more about function than flashy looks. The Century didn’t even get Buick’s stiffer Grand Touring suspension or 16-inch wheels.

If you wanted a Buick that was a bit more sporty, that was the job for the mid-size Regal, which originally launched as a 1997 1/2 model, which confused journalists at the time because there wasn’t any real reason for the half to be there. Here’s what MotorTrend said:

The new Regal sedan comes in two tangy flavors-Regal LS and Regal GS. Select an LS and you get the 3.8-liter/195-horsepower V-6 with 220 pound-feet of torque. Gutsy and quiet, this engine provides excellent acceleration and outstanding fuel efficiency at an EPA-rated 19/30 city/highway mpg.

Consider the supercharged 3800. It’s rated at 240 horsepower at 5200 rpm with a V-8-style 280 pound-feet of torque at just 3600 rpm. The GS we tested used this firepower to leap to 60 mph in just 6.6 seconds. This engine, with its Eaton 90 supercharger, is bolted to a beefed-up four-speed automatic, called the 4T65-E. Incredibly, with this engine’s bounty of power Buick estimates the GS’ EPA-rated fuel-economy numbers at 18/28 city/highway mpg. With the premium 4T65-E transaxle, drivers can push a gear-selector-lever button to get higher-rev, performance-style shift points for more spirited road running.

Buick has built the Regal on essentially the same platform and suspension as the Pontiac Grand Prix, so comparisons in terms of ride, structural rigidity, handling, and size are inevitable. But there are important differences. For example, Buick uses four unique rubber isolation bushings between the independent rear suspension’s subframe and the body to reduce road noise and vibration. Pontiac, however, bolts the crossmember directly to the body. And although the front MacPherson struts and lower L-arms basically are identical to the Grand Prix arrangement, Buick has selected much softer rubber suspension bushings. In addition, the Regal’s spring rates and shock damping system are completely different, for handling that is decently crisp without harshness. For more-mainstream buyers, the LS has softer bushings than the GS for an even plusher ride.

According to MotorTrend, Wayne Kady, chief designer of Buick at the time, said: “The ‘9711/42 Regal has an original, all-new, youthful look specifically designed to be the most expressive sedan in the Buick line.”

Motortrend responded to that by noting that, sure, the Regal did look pretty spiffy, but unlike a boy racer tuner car, the Regal wasn’t adorned with scoops, huge wheels, wings, or an intense body kit. The supercharged 3800 made the Regal GS move with a gusto that wasn’t far behind Buick’s old performance coupes, but the Regal’s design looked like something that your parents would have had no problems taking to church on Sunday.

But for some, that was the problem with the Regal of the 1990s and 2000s. It could hit 60 mph in 6.6 seconds, and it had a nearly bulletproof supercharged V6 that was easily tuned for more power. However, it was wrapped up in a cushy, inoffensive sedan that felt like it had recliners for seats. Period reviews often pegged the Regal as being a “sport sedan,” with Canada’s Driving saying that the Regal was “at least in the same realm as many European touring cars.” The Los Angeles Times said:

You don’t sling a Regal GS around against a Bimmer; but at stop lights alongside Accord, Camry and Taurus owners, you should be able to sneer with intent to commit much mischief. Although you might like to cover that AARP decal in your rear window.

Of course, I have to give you MotorWeek‘s take:

Most reviewers seemed to agree that while the Regal was pretty quick, it was mostly only quick in a straight line. The Regal GS also didn’t quite have the looks that young people were looking for, and some even wondered if making a sporty sedan was even the right move for Buick, considering its older demographic of buyers.

Still, Buick tried to relight some of that old fire, anyway. In 2000, Buick teased the world with the Buick Regal GNX Concept, which took the Regal and gave it a dropped suspension, a wing, upgraded brakes, sporty wheels, and a power bump to the supercharged 3800 to 300 HP and 300 lb-ft of torque.

This concept didn’t go anywhere, but it did prove the tuning potential for the 3800. It also proved that, with a little bit of tweaking, the Regal’s looks could be spiced up considerably.

Once The Fastest Buick Since The GNX

If you happened to be someone who wished the Regal GS was just a bit spicier, the car for you arrived in 2002 thanks to SLP Engineering. As The Car Connection wrote back then, the Buick Regal GSX was similar to SLP’s other project at the time, the Pontiac Grand Prix GTX. This, as the publication notes, is because both cars share the same platform, and thus nearly the same mods from SLP. However, of the two, the Buick was more of a sleeper because it didn’t have loud badging or graphics like the Pontiac.

SLP, which was founded by drag racer, hot rodder, and go-fast parts slinger Ed Hamburger, has been around since 1987. The firm didn’t manufacture cars, but for a long time had a deep relationship with America’s OEMs and often offered warrantied firepower at times when the automakers themselves did not. Back then, SLP was best known for its work on the Camaro and Firebird.

This time, however, SLP decided to bring back a famed Buick nameplate from the dead.

Back in 1970, Buick sold a muscle car in the form of the Skylark GSX, which housed a meaty 455 cubic-inch V8 under its hood that, when equipped with the optional Stage 1 package, pumped out 360 HP and 510 lb-ft of torque. The Audrain Automobile Museum has more details:

The Buick GSX Stage 1 was built to show that the performance features found in their popular Wildcat and Riviera GS models could also build and sell a muscular mid-size car in a very competitive market. The Skylark GS Line of mid-sized Buick coupes were upgraded with large displacement powerplants to create the GSX model cars and then taken one step further with the release of the limited production Stage 1 option package. Besides the engine upgrade to the massive 455 V8, a hood mounted tach, front and rear spoiler, race style gauge package, and wide black race stripes put the Stage 1 squarely in competition with other GM muscle cars like the Chevelle, GTO, and 442.

For 1971, Buick added the brand new 455 cu in engine into its restyled GS. The Stage 1 package had an even hotter cam, bigger valves in special high-compression heads, a distributor with a different timing curve and a modified Rochester carburetor. 455 big blocks retained the choice of a 4-speed manual shifter or 3-speed automatic on the floor.

It was widely suggested that the 360 horsepower and 510 lb. ft of torque claimed by the builder was underrated by a lot to address rising insurance cost and fuel economy concerns. Most people, including NHRA determined that the engine achieved over 400 horsepower. Running a 13.38 E.T. and reaching 105.5 mph in the quarter-mile, this prompted Motor Trend Magazine to name the 1970 GSX “The Quickest American Production Muscle Car”.

The use of the GSX name was fitting because, in turning up the taps on the Buick Regal GS, the folks at SLP made the fastest stock Buick money was able to buy in 2003. Period reports went even further, saying that the GSX was the fastest Buick since the 1987 GNX.

A lot of SLP’s changes were pretty mild. The GSX had 17″ by 7″ sport wheels, a wing, a slightly revised rear end, slight revisions in the front end, and a smattering of GSX badges on all corners of the vehicle. These were mild changes, but at least to my eyes, the GSX looked pretty close to the GNX Concept that Buick had teased a couple of years before.

Inside, more mild changes continued, including the addition of real burled wood finish trim as well as GSX logos for the headrests.

The real magic was what was underneath, and SLP sold the performance part of the GSX package in three Stages. The Stage 1 kit added a cat-back exhaust and a cold air intake, which added 15 HP to Regal GS and LS models. Stage 2 added everything from Stage 1, plus a Hypertech Power Programmer “with SLP Custom Calibration,” and a 180-degree thermostat. These changes netted the GSX an extra 20 horsepower.

Finally, there was the flagship Stage 3, which added all of the bits from the previous two packages, plus either “1.8 Higher Ratio Rocker Arms and Pushrods” for the Regal LS-based LSX, or “3.5 Inch Smaller Diameter Pulley speeds up the supercharger for more boost, more power, and more fun” for the GSX. The Stage 3 kit added 25 HP to Regal LS models and 30 HP to GS models for a max output of 270 HP and around 312 lb-ft of torque. One report from Autos Cheat Sheet claimed that these power figures were “conservatively rated,” but I have not seen any dyno data confirming otherwise.

From there, if you wanted your GSX to be even faster, SLP had options including BFGoodrich g-Force T/A KDW tires, Hawk brake pads, stiffer stabilizer bars, and a 1-inch suspension drop. If you checked every box, you ended up with a Regal GSX that was about as close to the GNX Concept as you could buy from a Buick dealership with a GM-honored warranty and a 50-state emissions certification.

A Real Tire-Shredder

While I could not find a period review, here is a story from the Autos Cheat Sheet:

At the 2015 Buick GS Nationals in Bowling Green, Ky., Turbo Regals and Skylark Gran Sports were lined up at Beech Bend Raceway as far as the eye could see. The sight wasn’t anything new at the 35th annual Buick event, as the two heavyweights have long been regarded as the brand’s greatest performance cars. The 1970 455 Stage 1 powered Skylark GSX is widely regarded as the king of the muscle car era, while the 1987 Regal GNX reigned supreme in the 1980s. But hidden among the sea of Grand Nationals in the staging lanes was Dirk Shultz, in one of Buick’s best-kept secrets.

As the unusual black silhouette made its way to the front, it was unidentifiable to all but the die-hard Buick enthusiasts. With a trip around the water box, the Buick quickly did its burnout and pulled up to the Christmas tree. The exhaust note was far too quiet for a V8, and the smoke rolling off the front tires raised a few eyebrows from those sitting in the grandstands. From behind the wheel, Shultz took the perplexed looks in stride. In his first ever trip to the GS Nationals, he decided to leave behind his 1971 Skylark GS 455 and 1987 Grand National in order to bring something unique that nobody else would have. After continually fielding questions about his mysterious car throughout the weekend, it was safe to say his mission was accomplished.

As the light flashed green, Shultz eased into the throttle to prevent lighting up the front tires through the first 60 feet. As any experienced drag racer will tell you, “if you’re spinning, you ain’t winning.” The four-door Buick quickly disappeared down the track with the faint whine of a supercharger and crossed the line in 14.34 seconds at 95 miles per hour. A blown front-wheel drive Buick? Was this some sort of joke? Not quite. This was a 2003 Buick Regal GSX — a four door sport sedan enhanced by Street Legal Performance. In 2003, SLP took a limited number of supercharged Regal GS sedans from Buick showrooms and performed an extreme makeover. The suspension was modified with lowering springs, larger diameter sway bars, and tubular rear trailing arms.

The only review I could find is a modern take:

SLP’s marketing was ambitious with the GSX. One part of the marketing copy says:

“Out on the road, GSX runs step-for-step with the much more expensive boys from Germany and the upstarts from Japan. At the end of the day, the only difference is the competition will be left scratching their head as you pull away in your GSX.”

The marketing also said that the “GSX is true to its Buick heritage,” and gave imagery of a rocket launch alongside photos of the GSX’s performance parts. It would be easy to dismiss SLP and the Regal GSX, but if you’ve driven one of these W-bodies before, then you know they are surprisingly capable out of the box and can be turned into something much more without a ton of work. These cars are perhaps not on the level of a German sport sedan, but better than their sedate looks would have you believe.

Sadly, I could not find any pricing details for the model. SLP sold the GSX from 2003 to 2005, and while production data hasn’t been released, it’s believed that legitimate GSX models are rare. With that being said, it was also possible to make your own GSX through the SLP catalog. SLP sold all of the parts separately, so any 1997 to 2005 Regal could be made into a Regal GSX clone.

The only way to know if you’re looking at an official GSX is by looking for the SLP sticker in the door jamb. Of course, a 2000 Buick Regal GSX SLP technically doesn’t exist, so checking model years is another way to tell.

Sadly, I found exactly zero GSX SLPs for sale. I haven’t even found archived listings for sold examples from within the past decade. The best I could find is a for-sale listing from 2009, when the seller didn’t get any bites until they dropped the price to $4,500. Oof. None of these cars has graced the pages of Bring a Trailer, Cars & Bids, or Mecum.

If you’re one of the people who love this era of GM, this car could be your next white whale. It came from a time when Buick sold cars that looked like they were for your grandparents, but hid excellent reliability and tuning potential within. Sure, these Buicks perhaps didn’t quite live up to the promise of besting the Europeans, but they’re still darn good cars. If you’re lucky enough, you might be able to find the fastest Buick of the 2000s and maybe surprise someone at the next car show.