Chadwick, appointed development driver for British Formula One team Williams last month, increased her lead in the inaugural championship to 68 points, 13 ahead of Visser who finished second.
“It felt like a long race for me,” said Chadwick, who also won in Hockenheim last month. “I just didn’t want to make any mistakes. In the previous races, I’ve always made like one or two mistakes so I just wanted to be really disciplined, not make a mistake.”
Behind Chadwick, fellow Briton Alice Powell crashed out of the race with a broken suspension and wheel after colliding with the slow-starting Wohlwend and going briefly airborne.
The incident brought out the safety car but when racing resumed Chadwick comfortably pulled away with Visser and Wohlwend close behind, the trio clearly benefiting from starting on fresh tyres.
The six-race series, which uses identical Formula Three cars for all the drivers, is aimed at helping women up the motorsport ladder. The overall winner will collect $500,000, with prize money down to 18th place.
(Reporting by Ian Page; editing by Clare Fallon)
