Complex sentence: The Audi RS 6 quattro, commonly referred to as the RS6, is a mid-size sports-focused executive car, produced by the high-performance private subsidiary company quattro GmbH, for Audi AG, part of the Volkswagen Group.
Split into simpler sentences: The Audi RS 6 quattro, commonly referred to as the RS6. It is a mid-size sports-focused executive car, produced by the high-performance private subsidiary company quattro GmbH, for Audi AG, part of the Volkswagen Group.