According to a list I have there are 103 Vintage Register eligible cars known, most of which are on the road. That's out of a total of approximately 1938.
Well 11581 triple M’s have been built and currently 3556 are registered according to the register database (link can be found on the home page) Though some of those registered will not be on the road some on the road are not on the register but I would gues it is a near enough guess