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.
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.
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.
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.
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.
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.
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.
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.
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.