Linking to facts may prove difficult, as it was recently on an A&E Special I watched entitled Modern Marvels: The Autobahn.

I did find a link to it here (in VHS format), which tells me that it MIGHT not be as current information as I understood it to be when I watched it, but they definitely made the claim.

http://store.aetv.com/html/product/index.jhtml?id= 43554