World's biggest car museum: La cité de l'automobile, in Mulhouse, France

520 cars from 98 brands, incuding the world's largest collection of Bugatti's (123) including three of the 7 Royales

the next 3 biggest museums are all in Germany, the Audi, Porsche, and Mercedes museums

https://commons.wikimedia.org/wiki/File:Collection_Schlumpf.jpg