Forty years ago, permanent all-wheel drive began its triumphant advance in passenger cars. Audi used the drive concept in large-scale passenger car production for the first time. It started with the original Quattro, but gradually the 4x4 concept became established in all model series. How have the cars aged, which ones have an exceptional status? Are there alternatives to the original Quattro? This report looks back to the beginnings and traces the career of all-wheel drive in Audi passenger cars.