Team mate Kamui Kobayashi held Sebastien Buemi off for second, while Buemi defended from Magny-Cours winner James Jakes.
The remaining points scorers were Jean-Carl Vernay, Franck Mallieux, Dani Clos and Renger van der Zande. The latter will start tomorrow’s race from pole position.
A first lap crash between three cars took Tim Sandtler out of the race and sent Nico Hulkenberg and Tom Dillman to the pits for repairs.
Grosjean now leads the championship by two points from Buemi.