Get 1999 Audi A6 2.8 Quattro Specs Detailed features and specs for the used 1999 audi a6 including fuel economy, transmission, warranty, engine type, cylinders, drivetrain and more. Gas mileage, engine, performance, warranty, equipment and more. 1999 Audi A6 Avant quattro 2.8 from media.automanager.com Wheel size for the 1999 audi a6 will vary depending on model chosen, although keep in mind that many manufacturers offer alternate wheel sizes as options on many models.