sentences:  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.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.Since 2010 however, Audi S models have been positioned more as optional engine trims.