10 Unreliable German Sports Cars With Ridiculously High Maintenance Costs

May 21, 2023

Carmakers, such as Audi, BMW, and Porsche, are well known for producing reliable sports cars, but some models are less dependable than others.

German cars are often loved and appreciated for their great performance and driving experience. While German carmakers like BMW, Audi, and Porsche are reputed for making powerful and luxurious sports cars, it's not all smooth sailing for the owners. While there are many German cars known for their strong long-term reliability and easy maintenance, a number of other models are infamous for their expensive repair costs and poor reliability.

Models with poor reliability not only have a low demand in the used car market, but also fetch a significantly low resale value. German engineering is not only difficult to fix when something goes wrong, but it also requires patience and a wallet full of cash. Having said this, here is a list of 10 unreliable German sports cars with ridiculously high maintenance costs based on reliability ratings and maintenance reports available on JD Power and Cars.com.

The 2006 Mercedes-Benz S65 AMG is well appreciated for its performance, in-cabin comfort, long list of features and a sophisticated package. Under the hood, the Mercedes-Benz S65 AMG is offered with a hand-built V12 engine that delivers a peak power and torque output of 621 hp and 738 lb-ft, respectively. This engine comes mated to a five-speed automatic gearbox. The S65 AMG also comes with a number of complicated components including twin sliding calipers, ceramic composite brake discs, massive twin exhausts and more.

Having said this, the 2006 Mercedes-Benz S65 AMG is also infamous for its expensive maintenance and poor long-term reliability, which keeps burning a hole in the owner's account. With a JD Power Consumer Rating of just 79 out of 100, the 2006 Mercedes-Benz S65 AMG is not the best car for those looking for a robust and well-built workhorse. Spare parts for the car are not only expensive, but are difficult to source as well. What makes thing worse is a poor fuel economy from the V12 engine.

The 2008 Audi R8 V10, unlike many other performance models in the brand's lineup, is known for its poor reliability and expensive repairs. Powering the Audi R8 V10 is a 5.2-liter V10 engine that produces 525 hp and 391 lb-ft of maximum torque. This V10 comes mated to an R-Tronic automated manual transmission which gets multiple modes including Sport and Normal.

Owners of the R8 V10 model report frequent problems with the ignition coils and suspension failure due to wishbone issues. In addition to this, the bearings are also prone to premature failure and are expensive to repair.

The 2005 BMW M6 V10 was launched in the market as a powerful and a dynamic offering in the market, but soon lost its charm due to a number of mechanical issues and expensive repairs. The M6 came with the V10 S85 engine, which was also regarded as one of the worst engines ever made by BMW. This engine delivers a peak power output of 507 hp and 383 lb-ft of maximum torque.

The V10 S85 engine suffers from a number of issues related to rod bearings, throttle actuators, SMG transmission, and valve cover gasket oil leak. While the road bearings cost over $1,000, buyers spend over $2,000 in labor for repairs. The throttle actuators, on the other hand, cost close to $2,000 to repair, while a transmission failure might put up repair bills close to $800. In addition to this, a number of other issues are also common with the 2005 BMW M6 V10, making it expensive and difficult to maintain in the long run.

Related: 5 Of The Best Mercedes-AMGs Ever Made (And 5 BMW M Cars We’d Rather Have)

Regarded as one of the most demanded and loved classic cars on the used market today, the Porsche 968 gets a long list of USPs in addition to its strong performance and dynamics. What the Porsche 968 is not known for is good long-term reliability and user experience, as owners report multiple issues and expensive maintenance costs. The Porsche 968 was offered with a 3.0-liter engine that makes 237 hp and boasts a claimed 0-60 mph time of just 5.9 seconds.

This performance car is infamous for its expensive service bills and has plenty of known issues with the water pump, timing belt and camshaft. The complicated dual-mass flywheel setup is also prone to frequent failures and is difficult and expensive to repair. The consumer reports too are not very impressive, and the Porsche 968 is definitely a car which should be left alone by those looking for a dependable and reliable performance car.

Right from the launch, the 2001 Mercedes-Benz CL600 was a popular car in the market for its power-packed performance, feature-rich cabin, and stellar looks. Under the hood, it was offered with a 5.5-liter twin-turbo V12 engine that churned out 510 hp and 612 lb-ft of maximum torque. What made things even more special were a series of electronic features, which improved the in-cabin experience by a significant margin.

Having said this, while the tech-laden cabin might sound luxurious for many, the 2001 Mercedes-Benz CL600 is infamous for poor reliability and expensive maintenance. Features like the active body control system are known to fail at frequent intervals, while other components like ignition models and coil packs are also not very reliable either. Most of these components are hard to source and expensive to replace.

The VW EOS Turbo was the first hard-top convertible to be sold in the market by the German carmaker and soon became popular for its looks. The 2007 VW EOS Turbo was offered with two engine options – a 2.0-liter turbo four-cylinder engine and a 3.2-liter V6 engine.

While the convertible setup was one of the highlighting factors of the EOS Turbo, it is also infamous for its lid's mechanism issues that are common to most units. In addition to a faulty convertible lid mechanism, the 2007 EOS Turbo is also prone to frequent leakage issues and electrical problems. Owners also report multiple issues related to carbon buildup in the engine, in addition to problems related to a diverter valve and intake manifold. The car scored a JD Power Quality and Reliability Score of just 57 out of 100.

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The Mercedes-Benz SL-Class was launched in the market for those looking for a powerful, fun-to-drive, and stylish convertible. This luxurious two-door convertible was offered with a number of engine options and boasts strong performance and dynamics. What is common to all the engines, however, is poor reliability and expensive service costs. The complicated and sophisticated setup along with German over-engineering makes the 2002 Mercedes-Benz SL-Class difficult to fix and maintain in the longer run.

With an expected annual maintenance cost of around $3,633, the 2002 Mercedes-Benz SL-Class is not only expensive to maintain but also requires frequent visits to the workshop. Availability of parts is not the best, and owners report expensive service costs. Furthermore, the fuel economy is not great either and most of the engines are known to be fuel guzzlers.

The Porsche 718 Boxster is appreciated for its strong performance and sporty looks, which makes it a great car for those looking for an aggressive and fun-to-drive car. While the 2017 Porsche 718 Boxster is a phenomenal sports car for the hardcore driving enthusiasts, it struggles with poor reliability and expensive maintenance costs.

Owners report an average annual maintenance cost of around $4,200 due to expensive spare parts and high labor costs. The 718 Boxster is infamous for problems with the airbags, engine, suspension, and fuel system.

The Brabus Smart Roadster Coupe was launched in the market as a light-weight and compact sports car. A unique and bold styling along with prominent styling elements like round headlamps gave this car a strong identity. Despite featuring a 101-hp 698 cc engine under the hood, the Brabus Smart Roadster offered impressive performance and a fantastic ride, all thanks to its lightweight chassis. The top speed was limited at 122 mph.

The car, however, is known for its poor build quality and water ingress issues. Cheap plastics and flimsy interiors require frequent maintenance and contribute significantly to the overall service bills. The poorly built gearbox is also difficult to fix, while the engine gives up around the 60,000-mile mark. The JD Power consumer ratings for the Brabus Smart Roadster stand at 83 out of 100 while the resale value is reported to be lower than other cars of the segment.

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The BMW Z3 was the last analogue car to be produced by BMW and is still appreciated for its strong performance and impressive dynamics. A powerful engine and a slick-shifting five-speed ZF manual gearbox made the Z3 a great car for driving enthusiasts. Under the hood, the 1996 BMW Z3 was offered with a 3.2-liter inline six-cylinder engine that is capable of producing 240 hp.

Owners report expensive service costs for the 1996 BMW Z3, while the parts too are expensive to replace. While the reliability is good for a car of this class, many of the models have issues with the radiator tanks, as they are known to leak and split. Preventive maintenance, however, can improve the reliability by a fair margin and bring down the maintenance costs by a significant margin.

An engineer by education and a motorhead by heart, he loves spending time behind the wheels. In the age of SUVs and crossovers, he still adores old-school low-slung sedans and drools over the Mustang '69.