Mowlem won the 2005 UK Reading Sports Personality of the Year, an honour reserved for the top sports performers in his region. Mowlem showed his adaptability during the 2006 season, racing an Aston Martin DBRS9 for Autosport Design Racing in the SPEED World Challenge GT series as well as competing in the International GT Open series in a Porsche and in two different classes in the ALMS. The latter led to one of the highlights of his career. Racing in the ALMS, Mowlem won the GT2 class at Mosport in a Ferrari, and then drove for the factory Zytek team in the LMP1 class in the last two races of the season. Teamed with former Formula One driver Stefan Johansson and Japanese Haruki Kurosawa, Mowlem finished second overall in the Petit Le Mans at Road Atlanta and nearly won the season finale from pole position, again with Johansson, at the newly renamed Mazda Raceway Laguna Seca.