That'd be the Esders Roadster recreation Rhys. The original Esders Roadster is chassis 41111, which was re-bodied early in its life to become the Coupe de ville Binder when owned by a French politician. This is how it has looked ever since. I believe this car is currently owned by Volkswagon who use it as a show-case, as they also own Bugatti.
Because they'd attained so many Bugatti parts, the Schlumpf's started having a recreation of the Esders Roadster built in 1965, and using original drawings from Molsheim. Apparently it took five years just to complete the engine and chassis. When the Mulhouse factory was raided by the workers in 1977, it still hadn't been completed. It was quite close to completion in 1977, but obviously this was then delayed many years after the take-over.
This is what the recreation looks like now. Its displayed at the entrance to the main hall.