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Reaching these cars' aftermarket potential may cost a fortune, but the results are well worth the investment.

German cars are known for their well-built engines, luxurious interiors, and iconic looks. Many of the fastest vehicles from the central European country command a pretty penny, like the 911’s $101,000 starting price. But despite the tremendous cost, they remain some of the most popular cars in the world. Several performance-minded German cars have almost unlimited tuning potential that pushes what’s possible.

Porsche, Mercedes, Volkswagen, and Audi all produce cars that have unlimited tuning potential with some simple modifications, upgrades, and ECU flashes. Unlike their Japanese counterparts, many of these German cars start with powerful engines. Regardless, the 1000 horsepower mark is no match for these tuner cars!

Because of their luxury and high starting power, tuning a German car costs an arm and a leg. However, the results are precision machines ready to tear the competition apart.

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Performance and luxury are buzzwords that describe Porsche’s lineup. The iconic Porsche 911 has several factory-direct performance editions, like the new GT3 RS. Still, a base model 911 has almost unlimited tuning potential, making it almost affordable and incredibly powerful.

Take the standard 379 horsepower 3.0L flat-six and supply some ECU performance chips and some forced air induction, and you’re bristling with power. However, more popular still are the tuning stages wealthy owners can purchase that feature upgraded cams, gearboxes, and other upgrades to hit well over 1,000 horsepower.

The Volkswagen Golf is one of Germany’s most popular tuner models that include performance-minded trims like the GTi and R. It also has almost unlimited tuning potential thanks to ECU tuners, like those from Cobb, and plenty of other aftermarket parts.

Popular upgrades to the Volkswagen Golf include turbo/superchargers, lowering coils, and various engine components. The engine block, cams, and pistons are solid to tune for well over 300 horsepower, especially the GTi and R variants.

Once upon a time, the Mercedes-Benz 500SEC was an expensive top-of-the-line S-Class sedan/saloon. Now, it’s a somewhat affordable German masterpiece with almost unlimited tuning potential, thanks partly to the beautiful V8 engine that can easily hit 350 horsepower.

The 560SEC has a decently easy engine to work on, and bolt-on mods provide some pretty decent gains. Tuning the engine will unlock even more significant gains. It looks great, has plenty of aftermarket support, and is a Mercedes. What’s not to love about the 560SEC?

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The Volkswagen Beetle is the Civic equivalent for the German population, with literally unlimited tuning potential. Anyone with enough cash, and patience, can craft anything they want out of the iconic “people’s car.”

A Volkswagen Beetle comes with an effortless engine to service. And the boxer engine has almost unlimited tuning potential thanks to the generous aftermarket parts. Plus, you can’t go wrong with those classic looks, and with a sufficiently tuned Beetle, you’ll be blowing sports cars out of the water!

A BMW M5’s journey to unlimited power has a giant step up thanks to a massive V10 hiding under the hood. In addition to the V10, the M5 (E60) has plenty of bolt-on modifications like intakes, which can push power well over 600 horsepower.

Because the V10 engine is naturally aspirated, the BMW M5 has almost unlimited tuning potential. Aftermarket ECU tuners and other parts provide a boost in power. Still, the $25,000 price tag is really attractive to tuners.

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If you’re a fan of the Subaru WRX, you probably find that BMW 328s and 330s want to race. That’s because the E46 BMW 3-Series is a German sedan with almost unlimited tuning potential. ECU tuners and aftermarket chips are just the beginning, and tuners have found ways to unlock crazy power from the 3-Series.

The E46 BMW 3-Series is popular among tuners for the ability to upgrade the ride height, air induction, and suspension. That’s not even including engine tunings like cams, pistons, and headers.

Audi’s RS3 is unique in terms of its stock engine. Under the hood, the RS3 sports a five-cylinder engine that, before tuning, pushes 401 horsepower. Plenty of aftermarket tuners, turbo/superchargers, and virtually unlimited tuning potential.

Tuners of the Audi RS3 benefit from several stage kits that offer horsepower ratings topping 540 horsepower. In addition to stage kits, you can even tune engine components like cams, intakes, and exhaust to push well past 650 horsepower!

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The Mercedes-AMG A45 S proves that an inline-four can have unlimited tuning potential. The A45 S has the world’s most potent inline-four—the 421 horsepower, 2.0L M 139. With all that power, it may seem silly to tune. However, that number can be even higher, even without internal swaps.

Those internal swaps would include things like upgraded cams and air intakes. Not to mention, with all the body mods that improve times, the AMG A45 S is worthy of crazy tuner attention.

The Mercedes-AMG E63 S is already a monster of a German machine but can get even crazier. It has tons of great specs, to begin with, like a twin-turbo V8 that pushes 603 horsepower stock.

Tuners love to add upgraded internal parts and more robust turbochargers that push that 603 horsepower to well over 700. The AMG E 63 S has plenty of room under the hood for intakes, and many aftermarket tuning chips promise up to 30% increases in power. We’re skeptical of that high of a boost, but there’s little doubt that the E63 S has almost unlimited tuning potential.

The Panamera Turbo S is not the best-looking Porsche around. It’s downright ugly, actually. But, it comes with a mighty, twin-turbo V8 that cranks 620 horsepower. However, with deep pockets, you can crack 700 horsepower.

Many popular upgrades include turbochargers, exhaust manifolds, and high-flow air filters. With the additional air, it only makes sense that excessive power comes from this precision German automobile.

Michael Stroup is a seasoned automotive author with experience in SUVs, Trucks, and JDM sports cars. He credits his passion to gearhead friends and active involvement with car-related ghostwriting assignments. You can find Michael in the mountains, where he dedicates time to snowboarding, hiking, or off-roading!