Of course the really old stuff has a century's worth of miles on them, but how about the new stuff? This Brooklands came up for sale again about 2 years after this post was written: http://pursuingwo.com/many-miles-put-limited-edition-exotic-car/
It hasn't been driven much at all in the past two years, but its first owner logged about 10,000 miles per year with it. Are you conscious about how many miles you put on your Bentley? What is the right amount? Or do you just drive?