AgencyPower Agency-Power-Blow-Off-Valve The Audi allroad quattro and the subsequent Audi A6 allroad quattro are crossover-styled estate executive cars, produced by German automaker Audi since 1999. Based on the Avant version of the Audi A6, the A6 allroad quattro remains in production for Europe, but not for North America as of December, 2008.