<P> In the past, some Audi S models competed directly with BMW M and Mercedes - AMG models, such as the B6 Audi S4 4.2 FSI versus the BMW M3 and Mercedes - Benz C32 AMG. (1) Since 2010 however, Audi S models have been positioned more as optional engine trims . For instance the base Audi A4 (B8) engine is the 2.0 TFSI turbo four - cylinder, and with the discontinuation of the 3.2 FSI V6, that makes the Audi S4's 3.0 TFSI V6 the performance option (the B8 Audi S4 3.0 TFSI positioned closer to the E90 BMW 335i than the BMW M3). The Audi A6 (C7) no longer has a V8 engine upgrade in the non "S" range, with the discontinuation of the C6 Audi A6 4.2 FSI that was offered from 2004--2011, one must go to the C7 Audi S6 4.0 TFSI (2). </P> <P> Audi "S" models should not be confused with the Audi "A, Q, TT" series, equipped with a package "S line" models, which feature leather trim, S - line badging, sports steering wheel and sports suspension, but they are not equipped with a high - power engine . </P> <P> 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". The characteristics and cost of these cars are close and equal to cars belonging to the supercar class . </P> <P> RS is Audi's highest performance' top - tier' trim level, positioned distinctly above the "S" ("Sport") specification level of Audi's regular model range . All "RS" cars pioneer some of Audi's latest and most advanced technology and engineering prowess, therefore, "RS" cars could be described as "halo vehicles". Audi RS cars are some of the most powerful vehicles ever offered by Audi as well as R8 . Audi RS 6 (5.0 TFSI quattro), for instance, is more powerful than the physically larger Audi S8 (5.2 FSI quattro) However, the 2012--2015 Audi S8 shares the same engine as the 2013--... Audi RS 6 and Audi RS7, albeit in a lower state of tune, while for the 2016--2017 model years, the Audi S8 plus features an uprated engine with the same output as the smaller RS 6 and RS7 . </P>

What does the r stand for in audi r8
find me the text answering this question