 His international career took off in 1983 in the IMSA series in the United States, with his most notable win in the 1984 24 Hours of Daytona race driving for Kreepy Krauly Racing, an all-South African team in a March 83G-Porsche.He shared the win with Graham Duxbury and Tony Martin.Van der Merwe did exceptionally well in the 1984 24 Hours of Le Mans where he finished 3rd on debut.