Time for "Historic" plates
The VIN plate on the door of my first-year Miata says that it was built in May 1989.
Which means that it's now over 25 years old.
NYS DMV says that I can get "Historic" plates for it in the next calendar year: so, January 2015. But it's already registered through March of 2016. (And "Historic" plates cost more.)
A quick Google doesn't turn up a VIN-decoder that will tell me the exact day it rolled off the line; but it seems to be around #4,0000 in the run. (The last I knew, production-to-date was in the 900,000 ballpark.)