Its a possibilty. However, Le Mans and Sportscars in general arent what they used to be for Technological Advances. If Peugeot were to rejoin F1, Im sure technologies would be passed down onto the mass market range.
As For Le mans, one example is that one of the LMP1 Teams, is using an Aston Martin engine, same one as in the DBR9.
However, I could be wrong. Look at Audi, theyve incorporated Performance Diesels into their range now, Surely helped by data, technology and experiences of running the R10s at Le Mans...
Thats the peugeot Engine... V12 (700bhp) as opposed to the V10 of the Audi..(650bhp)