Following Nissan's withdrawal from the BTCC at the end of the 1999 season, a potential drive for Honda fell through (that spot being taken by Tom Kristensen), he made the switch to the new Deutsche Tourenwagen Masters series, driving for the Abt Sportsline team in their Audi TT-R, a move that surprised some. The first season was unsuccessful, with no victories, as the Audi TT proved to be uncompetitive against the faster Mercedes-Benz CLK and Opel Astra rivals, its best finish being Aïello's fifth place at the second Oschersleben sprint race. He entered his third 24 Hours of Le Mans, driving for Audi, and finished second.