Most Extreme Rides

The Porsche 911 Turbo Sean Woodroofe bought as a present to himself on his fortieth birthday is the envy of most auto enthusiasts. Yet it wasn't enough to satisfy him.

Woodroofe paid another $30,000 to have his 911 Turbo modified by Porsche specialist Ruf, based in Pfaffenhausen, Germany.

"My conversion package increases original horsepower from around 420 hp to nearly 600 hp," says Woodroofe, vice president of human resources at Financial Guaranty Insurance Company in Manhattan. His car also features a revamped suspension, special front bumper, and a rear spoiler to improve aerodynamics.

Ruf is one of dozens of European performance-car tuners whose insane modifications inspire an avid following among hardcore enthusiasts.

"Going to Ruf is like going to Savile Row, you get it made for you," says Estonia Ruf, the company's vice president of sales and marketing, and wife of owner and managing director, Alois Ruf Jr. "Everyone who comes here wants something different. We walk them through the process like a builder does a house," she says.

Other noted German auto tuners include AC Schnitzer, Alpina, Brabus, Hamann, and Lorinser. They're mostly anonymous to the masses, but they might not be for long.

"From the mid-1990s to now, we've seen a boom in demand as more and more people see and learn about aftermarket tuning. In Europe, maybe 35 percent of all automotive articles focus on the aftermarket," Ruf says.

As a whole, the German automotive aftermarket does more business overseas — $3.74 million in 2006 — than in Germany — $3.58 million in 2006 — according to the most recent data from VDAT, a trade association representing the German automotive aftermarket. From 2000 to 2006, sales of German aftermarket companies increased by $716 million to $7.3 billion globally, says Hans-Jörg Köninger, general manager and board member of VDAT.

For a glimpse into this realm of outrageously fast cars whose performance, speed, and style are limited only by the money buyers are willing to spend, we've compiled a list of 10 of the most insanely modified vehicles from a cross section of European tuners. Go to the slideshow for the full list.

One of the most extreme vehicles on the list is a Mercedes-Benz SLR McLaren Roadster modified by German tuner Brabus for a total cost of $852,000. This includes the vehicle's suggested retail price of $495,000, plus a staggering $357,000 in upgrades.

Brabus, based in Bottrop, Germany, squeezes an additional 24 hp out of the SLR McLaren's twin-turbocharged V12 engine, for a total of 641 hp. But that's only the beginning of the transformation.

The suspension is reworked, a carbon-fiber front spoiler and air diffuser are fitted, and the interior is swathed in high-grade leather, including waffle patterned leather carpeting that requires 25,600 feet of thread.

Brabus, which specializes in modifying Mercedes models, works on more affordable vehicles too, including one of the most unlikely candidates: the $16,000 Smart ForTwo Cabriolet. For about $60,000, it decks out the diminutive two-seater with an aggressive body kit and a turbocharger for more power.

Like its competitors, Brabus sees a growing opportunity for high-quality aftermarket upgrades. "The evolution occurs in the increased amount of competition as tuning's popularity grows," says Claus Ettensberger, CEO of Brabus USA. "What was once accessible to a niche group is now available to the masses."

That said, our list proves the market for modifying high-performance European vehicles is heady. "Our clients tend to be wealthy — not billionaires, but they are all car-crazy, people who just love cars," Ruf says.

Ruf's CTR3, the second priciest vehicle on our list at a total cost of $510,000, is based on the Porsche 911 GT3 RS, but is so heavily modified that it's basically a different vehicle.

To create the CTR3, Ruf chops a $124,900 911 GT3 RS — a rare car unto itself — in half and grafts a new steel, aluminum and Kevlar-carbon structure to the rear. Bulging fenders and a dome-like roof transform the CTR3 into what looks like a race car. With engine modifications that pump up power to 700 hp, it also drives like one.

Considering that the modifications many European shops perform require dismantling an engine or an entire vehicle, the process isn't without risks in terms of reliability and safety. For this reason, most automakers will void original warranties of vehicles they know have been modified.

But this is where the German tuners' robust and methodical engineering practices help to improve a segment that is often considered the Wild West of the auto industry with a lowest common denominator that Ettensberger calls opportunistic "fly-by-night companies that sell fraudulent unsafe copies for mass consumption."

He stresses that German tuners must comply with stringent regulations and testing requirements similar to those major automakers adhere to. "This applies to wheels, tires, aerodynamics, suspension, and brakes for example," Ettensberger says. "I think knowing this fact makes first-time 'tuners' more comfortable and helps the broad public in understanding why European tuning products — especially German TUV-approved wheels and wind tunnel tested aero parts — are more expensive." (TUV is short for Technischer Überwachungs-Verein, the name of the German governing body responsible for ensuring product quality and safety.)

The best tuner-car companies warranty their work and have good rapports with the original automakers' dealer networks. Brabus offers a 3 year/50,000 mile warrantee similar to one that a new, non-modified Mercedes-Benz carries. "Any regularly scheduled maintenance can be serviced at your local Mercedes-Benz dealership," Ettensberger says.

Ruf's general warranty also covers 3 years or 50,000 miles. Plus, Ruf has a service specialist who will travel to the United States from Europe to diagnose and repair emergency issues.

"There aren't many places where you can pick up the phone and speak to the number one or number two person in the company when you have a problem," says Woodroofe, owner of the Ruf 911 Turbo.

But don't expect to just walk into any showroom and purchase a custom-tuned vehicle. For that, buyers must contact the tuning companies themselves and proceed in one of two ways: buy a factory vehicle from a regular dealer and take it to the tuner for customization, or buy a car that has already been modified directly from the tuning company.

As modifying cars' performance and aesthetics grows more popular, some see limitless possibilities. "I envision the day when the $5 million car will be built just for you," says Milton Pedraza, CEO of the Luxury Institute, a New York-based research firm. "People will start to pay for a one-of-a-kind, custom-made, custom-built car. Forget the Bugatti Veyron, the limited-edition-of-20 Lamborghini Reventon, we're talking one-of-a-kind, only built for you — ever. That's the future."

Our list of the Top 10 Most Extreme Euro Tuner Cars seeks to highlight the most extreme modifications each company currently offers, with a focus on a variety of makes and models.

Because auto tuners rarely make two identical cars, most of them don't publish pricing information — RUF is an exception. For most companies on our list, pricing data came through the tuners' sales offices in accordance with how much it would cost to reproduce one of their showcase vehicles.

Slideshow: Most Extreme European Tuner Cars