If the OP isn't dead set on grey, but just wants a modern color, besides what I previously suggested, there's the following: GM blue on new pickups that looks like the '68 Q1 but on steroids. They - and Mazda - also have reds like candy-apple red; the Mazda color pops from 200 feet away. FWIW, Steve Strope @ Pure Vision likes Aston Martin metallic colors, and his builds are generally attractive.
