It is Maurice Rost at the 1926 GP de Provence as Hiawatha correctly says. It won its class and finished 6th overall.
The car was fitted with a 3-litre engine but production of those engines did not begin until 1928, so maybe they used the race for testing the new motor. I am curious about the headlight. The race was held at the Miramas banked oval, so it is possible that the car was used after the race to attempt endurance records (running at night) or maybe it was driven down from the factory in the Seine departement.
