 In the 1970s, Ludwig drove for Ford in the Deutsche Rennsport Meisterschaft, winning in 1979 with a Kremer Racing-Porsche 935.With this car, based on the then 15-year-old Porsche 911 road car design, he won the 24 Hours of Le Mans overall in the wet, an unprecedented win against the faster pure sports car racing prototypes (though it was subsequently matched in 1995 when a McLaren F1 GTR won the race at its first attempt).In 1984 and 1985, he won the 24 Hours of Le Mans for Joest Racing in their #7 Porsche 956.