Well in the old version of the CS registry that's floating round, 3 of 98 cars that have a definite color are Argento. So extrapolating that out to the 360 or so US cars is 11 cars. So I'd guess somewhere between 10 and 20 in the US? (similarly only 9 of these 98 have a stripe, leading to my guess that only 30-40 US cars have a factory stripe).
