An automaker may think it's done the best that it could, but tuners know different. Every car coming out of the factory can get more speed and better handling, and throughout the years, tuners have proven the point. Here are 10 automotive tuners.
Originally an independent company founded by former Mercedes engineers to build racing engines, AMG has become a wholly owned subsidiary of Mercedes.
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Mercedes-Benz SLS AMG
The SLS AMG is the first Mercedes to be designed fully in-house by AMG and features a 6.2-liter V-8 producing over 560 horsepower. The gullwing-style doors hearken back to the original 300SL coupe of the mid-1950s.
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BMW's M division also started as a race-prep operation, although it was an in-house group from the beginning. Its first project was the 3.0CSL "Batmobile," which was very successful in the European Touring Car Championship in the early 1970s.
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The first M road car was the famed M1, a Giugiaro-styled two-seater introduced in 1978. Since then, most BMWs have eventually spawned an M variant, the 3-series being the most popular. BMW recently announced that the 1-series would get the M treatment for 2011.
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Lexus is a relative newcomer to the in-house performance division game, having launched its F-Sport designation in 2006.
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Lexus IS F
Lexus' first F-branded model was 2007's IS F, featuring a 5-liter V8 with 416 horsepower. The LFA supercar followed in late 2009.
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Ruf Automobile is actually designated a manufacturer by the German government, but it's essentially an independent Porsche tuning outfit. Ruf has been tweaking Porsches since about 1960, initially at the family's service station.
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Ruf's latest Porsche-based creation is the CTR3, introduced in 2007. With a midmounted, twin-turbo 3.8-liter flat-six, the CTR3 can get from rest to 62 mph in 3.2 seconds, according to Ruf.
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Callaway Cars was founded in 1977 by Reeves Callaway and initially produced turbocharging kits for various cars, eventually specializing in Chevrolets. From 1987-1991, Callaway's twin-turbo kit was a regular production option from GM for the C4 Corvette.
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Most recently, Callaway has turned its attention to the new Camaro, adding a supercharger to the stock 6.2-liter V-8 and bumping output to as much as 572 horsepower.
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Probably the most familiar name on our list, Carroll Shelby is best known for teaming with Ford to produce or help develop such legends as the Cobra, Daytona Coupe, GT350, GT500, and GT40.
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Ford Shelby GT500
The latest Mustang to boast the Shelby name is the 2011 Shelby Mustang GT500, with 550 horsepower and unique body elements. The GT350 nameplate is also being revived by Ford for 2011-12, featuring a supercharged V-8 with 525 horsepower.
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Initially formed as "Team Viper" to develop the Dodge Viper in the late 1980s, Street and Racing Technology (SRT) eventually became the performance division for Chrysler, Dodge, and Jeep.
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Dodge Challenger SRT
SRT's current offerings include the Dodge Challenger SRT-8, Dodge Charger SRT-8, Chrysler 300C SRT-8, and Dodge Viper SRT-10.
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Subaru formed its Subaru Tecnica International division in the late 1980s as in-house rally specialists, and has since won multiple WRC championships as a manufacturer and for its drivers.
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Subaru Impreza WRX STI
The Impreza WRX STI was the first production car to emerge from the STI division, making it to the U.S. in 2004. It has been very popular as a relatively low-cost performance car, and will once again offer a sedan body style for the 2011 model year.
17 of 20 Josh Miller/CNET
Yet another in-house racing division, Toyota Racing Development (TRD) develops race cars and engines as well as aftermarket street-car performance parts.
18 of 20 Josh Miller/CNET
Scion xD TRD
TRD produces cosmetic and performance enhancements for many Toyota products, like the Scion xD seen here.
19 of 20 Wayne Cunningham/CNET
Karl (later Carlo) Abarth founded his eponymous tuning and manufacturing operation in Turin, Italy, in 1949. Abarth began its long association with Fiat products in 1952, and officially became part of Fiat in 1971.
20 of 20 Wayne Cunningham/CNET
Abarth Punto Evo
The most recent product of the longtime Fiat-Abarth collaboration is the Punto Evo, shown at this year's Geneva auto show. The Abarth division aided in engine development for the model, which will be sold through Abarth-branded dealerships in some countries.