I'm sure others will describe it better…….
Its sort of like a summer fete type atmosphere but heavily centred around cars and those marques associated with Le Mans history. Each year is a different marque.
I attended the Lotus one a few years back.
A get together on the Friday before the race at a place called Saint Sturnin, just north of Le Mans.
Everyone turns up in their nice motors and parks up for an informal car show. There is food and drink on offer. And usually they manage to persuade some people to bring along some real exotic or historic cars to be on display.
Don't worry if you car does not 'fit', as they just park us out of sight and you are free to wonder around and dribble on the more fancy stuff.
Website seems a little out of date…….
http://www.classicbw.org/uk/index.php