What is the rarest Nissan Skyline?

What is the rarest Nissan Skyline?

There are a few notably rare Nissan Skylines; the Z-tune, R400, and of course Brian O'Conner's electric blue R34 from 2 Fast 2 Furious. But there's only one truly rare-as-unicorn-plop Godzilla: the awesome R33 LM.