Sports cars are great. They look terrific. They can reach speeds that would make anybody's heart explode. They are true head turners. Sadly, they tend to cost an arm and a leg not just to purchase, but also to maintain. Not everybody can fork out $100,000 on a car and spend over $15,000 on yearly maintenance. As a result, most gearheads with average finances will most likely settle for regular cars and give them the extra zing they desperately need.

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Modifying cars can become extremely pricey, depending on the car being customized and to which level its owner is trying to get to. However, some cars can become true beasts with just a couple of simple modifications. As if this was not satisfying enough, they tend to be affordable and so common that most people do not pay attention to them. These cars are the most badass project cars to modify into a sleeper.

10 2004 Audi A4

Audi's cars started getting extremely popular in the early 1980s. Similarly to BMW and Mercedes-Benz, Audi really put an emphasis on engineering sports cars that would conquer the world market. In order to cement its reputation as a serious carmaker, Audi enrolled its legendary Quattro Sport in the World Rally Championship. Following numerous victories, the Quattro Sport became an icon and allowed Audi to move forward with producing more sports cars.

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The A4 B6 should be among the most reliable cars Audi ever made. The 18-year-old car will still run despite having been around for so long. The best part about the 2004 A4 B6 is the 3.0-liter V6 that makes 217 hp and 221 lb-ft of torque. The power is transmitted to the wheels thanks to a five-speed transmission. This affordable marvel can be tuned to 400 hp with a simple JHM Stage 2 tune up.

9 2005 Volvo S60R

Gearheads tend to overlook Volvo cars as they have the reputation of being dull and overly safe suburban mom cars. Though it is true that Volvo has earned its reputation of being one of the safest carmakers in the market, the Swedish company has produced cars that look like grocery getters, but that would rock anybody's socks off. The whole world should thank Volvo's engineer Nils Bohlin for inventing the seatbelt, but they should also thank Volvo for coming with the R versions of the S60.

The Volvo S60r already seems more aggressive than the 2.4-liter T5 S60. In fact, the S60r comes stock with a turbocharged 2.5-liter five-cylinder engine that pumps out 300 hp and 296 lb-ft of torque. Those numbers are already impressive, given the fact that the S60r is perceived as a grocery getter. A R32 turbo kit from RZ Design tuned to produce 18.8 psi of boost will increase the power output of the S60r by at least 200 hp.

8 2007 Saab 9-3 Aero

Back in 2011, Saab kicked the bucket and stopped producing cars. As Saab was originally specialized in aerospace and defense, the company logically went back to its core business. Though most gearheads will not miss Saab cars, true European car fans know for a fact that Saab produced cars with tons of potential during its hey-days.

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The 2007 Saab 9-3 Aero is a beautiful sedan. It comes with gorgeous 18-inch wheels and dual exhaust tips. Underneath the hood sits a 2.8-liter V6 that makes a decent 250 hp and 258 lb-ft of torque. For $2,999, it is possible to obtain a turbo kit from VTuner that will increase the total output to 450 + hp. It will turn this sexy Swedish sedan into the perfect sleeper.

7 2012 Mini Cooper S

Whenever people think of the Mini Cooper, they imagine Mr. Bean goofily driving around London with his teddy bear. As time went on, Mini tried to shake off the image of being the producer of microscopic and unattractive urban vehicles. Things really switched up when BMW acquired Mini in the early 2000s. Today, Mini's lineup include some great project cars.

The 2012 Mini Cooper S is a cute urban vehicle that attracted the vast majority of trendy fashionistas. Most gearheads looked away from the Cooper S, and that is their mistakes. The turbocharged 1.6-liter inline-four engine cranks out 181 hp and 177 lb-ft of torque. Given the fact that the 2012 Cooper S is turbocharged, it is possible to simply replace the turbo and tune the ECU in order to get to 300 hp.

6 2013 Mazda MazdaSpeed 3

When looking at the Japanese car industry, it is easy to see that big-block V8s are not the name of the game. Though Japanese V8-powered cars do exist, Japanese carmakers have shown that they were perfectly capable of getting over 400 hp out of a small engine. However, the gentlemen's agreement that limited the power of any Japanese cars to 276 hp prevented just that from happening.

The MazdaSpeed 3 may not be one of the most important cars in Mazda's history, but it sure is a car that deserves every piston head's attention. The turbocharged 2.3-liter inline-four unit makes 263 hp and 280 lb-ft of torque. It is possible to get the MazdaSpeed 3 to produce 400 hp, but that requires a decent amount of work and money.

5 2016 Volkswagen Golf R

Volkswagen was originally created to become the people's car brand. While it is true that Volkswagen cars are the cheapest German cars out there, they have become less accessible. Brands such as Dacia or Škoda deserve the "people's car" moniker more than Volkswagen. In fact, Volkswagen has grown into a producer of decently-powered hatchbacks, sedans, and SUVs.

When the first 2016 Volkswagen Golf R was first released, Golf fans thought right off the bat that this bad boy can be tuned to annihilate a mid-range sports car. It is important to point out the fact that Volkswagen tuned the turbocharged 2.0-liter inline-four engine to produce 292 hp and 280 lb-ft of torque. There is a plethora of videos on YouTube showing Golf Rs producing over 500 hp with just bolt-on parts and a tune.

4 2017 Infiniti Q60

It is well-known that Infiniti is the luxury division of Nissan, in the same fashion that Lexus is the luxury division of Toyota. Over the last two decades or so, Nissan brought back the Z nameplate. Starting with the 350Z, Nissan hit the nail right on the head. Banking on its success, Nissan released the 370Z a couple years later. As both Zs were very successful, cars such as the Infiniti Q60 went unnoticed.

The 2017 Infiniti Q60 is a gorgeous luxury coupe. On top of being aesthetically appealing and luxurious, the Q60 comes with the same twin-turbocharged 3.0-liter V6 that makes 300 hp and 295 lb-ft of torque found in the Skyline and the Z-Series. Based on what has been done to the two Nissan's sports cars, it is fair to assume that the Q60 can easily become part of the 600 + hp club.

3 2020 Ford Mustang GT

Pony cars have been at the forefront of the American sports car scene for decades. Though between 1975 and 2005 pony cars were sadly disappointing, domestic were able to reverse the trend thanks to the technological advances that were made in the most recent years. In 2004, the Mustang GT was rated at 260 hp. In 2005, the power output of Ford's most popular pony car went up to 300 hp.

There are several things gearheads should know before buying a used Ford Mustang. However, if there is one thing that most Mustang GT owners know, it is the fact that a new air intake, a supercharger, and a complete exhaust system can turn the Mustang GT into a true beast. It is common to stumble across 550 hp Mustang GT as aftermarket performance parts are readily available. As a matter of fact, there are now too many parts to choose from.

2 2020 Toyota 86

Over the last 20 years, Toyota completely transformed its business model. The Japanese carmaker terminated cars that were not selling despite being popular among car fans. Leaving only cars such as the Camry, the Corolla, and the Prius, Toyota was able to hit the bottom line but lost respect in the car community. In an effort to rekindle the relationship Toyota had with genuine piston heads, the carmaker released the 86.

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The Toyota 86 is a great compact sports car. However, it has often been said that its 2.0-liter flat-four engine is highly sluggish. With a power output of 200 hp and 151 lb-ft of torque, it is true that the 86 is not packing much heat. Thankfully, it has been shown that basic modifications can bring the power output of the 86 to 350 hp without having to spend an insane amount of cash.

1 2021 Chevrolet Camaro SS

Chevrolet's Camaro is a tremendous vehicle. Some of the rarest and fastest Camaros are now worth hundreds of thousands of dollars, if not millions. Unfortunately, Chevy completely destroyed the Camaro when it released the fourth generation in 1993. The "catfish" Camaro was so horrible that Chevy retired the nameplate for eight years.

The Camaro SS comes with a 6.2-liter LT1 V8 that makes 455 hp and 455 lb-ft of torque. To most people, that is a lot of power. Any European car fans will not be able to wrap their mind around the fact that the Camaro SS starts at around $38,000. To most demented piston heads, the Camaro SS is just another Camaro that needs some serious power. Turning the SS into a ZL1? Say no more.