The Audi A4 is a spacious automobile. Its body, comprising mostly high-strength and ultra high-strength steels, is rigid, lightweight and safe. The sedan offers a trunk capacity of 480 liters (16.95 cu ft). Capacity with the rear seat backs folded down (a standard feature in the quattro versions) is 962 liters (33.97 cu ft). The A4 Avant offers 490 and 1,430 liters (17.30 and 50.50 cubic ft), respectively. The interior offers all of the classic strengths of the brand, with uncompromising fit and finish and logical, intuitive controls. When equipped with a navigation system, the A4 features a color monitor and the MMI operating system. Audi offers the luxurious climate-controlled comfort seats as an option for the driver and front-seat passenger. Small fans provide six-speed ventilation to the seat cushion and back.