In 1983, the company Quattro GmbH was founded (since November 2016, "Audi Sport GmbH") in the city of Neckarsulm responsible for the development of sports models of cars of Audi brand.

[4] Since 1994, the development of the Audi S and RS sports series was started directly from the Quattro.

These cars are recognisable by their "S" badges, and unique emphasis lines on their front grilles and on the back side, instead of the letter "A" in the designation of numbers and also in use in the notation "S3", and "SQ5".

[6] Unique internal combustion engines, along with larger, more powerful brakes, stiffer suspension systems, additional exterior body styling, and carbon fibre interior trims set them apart from their related "siblings" of their respective model range.

[9] Audi 'S' models should not be confused with Audi 'A' and 'Q' series models equipped with an "S line" package, which features sport tuned suspension and cosmetic upgrades such as leather trim, S-line badging, and sports steering wheel, but are not equipped with a higher-performance engine.

[5][10] Audi Sport GmbH (formerly quattro GmbH), AUDI AGs high performance private subsidiary, creates even higher performance versions, known by their "RS" badging.

The "RS" initials are taken from the German: RennSport — literally translated as "racing sport".

[14] Unlike Audi "S" models whose interiors are well-furnished in order to retain the feel of sport luxury, the interior of Audi "RS" models are often spartan by comparison as the emphasis is more on track performance than luxury.

The 2008 Audi RS 4 sold in Europe had lightweight racing-style front seats and roll-up windows for the rear doors, although its counterpart sold in the United States has luxurious power-adjustable front seats and power windows for all doors 2008 BMW M3 vs. 2007 Audi RS 4, 2008 M-B C63 AMG.

(Roadster) 2 dr, 2 seat compactRoadster (convertible) 1,570 kg (3,461 lb) 3.9 sec.

(Roadster) 2 dr, 2 seat compactRoadster (convertible) 1,605 kg (3,538 lb) 2,995 cc V6 TFSI 4.9 sec.

(Cabriolet) 5 dr, 4 seat Sportback (fastback) 2 dr, 4 seat mid-size Cabriolet 1,870 kg (4,123 lb) 1,915 kg (4,222 lb) 174 mph (280 km/h) 5 dr, 4 seat Sportback (fastback) 1,817 kg (4,006 lb) 2,995 cc V6 TFSI Audi produce a specification of optional sports trim packages to their mainstream models A/Q/TT, known as the S line.

[10] This is merely a trim specification which allows customers to effect a sporty appearance in their mainstream Audi model.

Whilst the specific S line trim parts are designed and produced by Audi Sport GmbH at its Neckarsulm factory, these mainstream cars are still manufactured and assembled by AUDI AG at their relevant factories on the same production lines alongside their other standard models.

Cars with S line trim are not to be confused with the specific high performance offerings — the "S" models (made by AUDI AG), and the "RS" models (made by Audi Sport GmbH); Audi cars with S line trim bear identical performance figures to their counterparts with base or SE trim levels.