The England midfielder’s switch will be completed when his World Cup campaign is over.
The mini vehicles are capable of 15 miles an hour.
Clark called last year’s incident at Oakmont the “lowest point” of his career.
Van Poortvliet has edged Alex Mitchell.
The Lancashire seamer impressed in Wednesday’s Vitality series opener against India, which was washed out.
Disciplinary panel finds Belgian’s ride on Puerto Rico was not intended to benefit Gstaad.