Thanks for the big hint
The rallye was between Posen (today Poznan, Poland) and San Sebastián (Spain). The 2355 km had to be done in 7 days. The car was made by Grégoire (a company based in Poissy, France) and was called "La Roulotte" (The Caravan). Despite carrying 11 passengers it finished first at September, 21 of 1912. A Hispano-Suiza came second. And that's not all, it also won the "Prix d' élegance" at San Sebastián
The driver was Jean Porporato and the team was led by Mr and Mrs Picard.