Both qualifying on Saturday and Sunday were a gamble on whether to put rain tyres, or to stay on slicks.
The new series looks to revolutionize the way drivers prepare during the off-season.
Emerson Fittipaldi joined his grandson, Pietro, at Siverstone.
On the final lap at the Brands Hatch Grand Prix circuit, Pietro Fittipaldi took his first victory in the BRDC F4 Series.
Backed by the world's richest man, grandson of Emerson will trade a promising career in the U.S. at age 16 to compete in single-seaters.