Codemasters recently announced that the PC edition will be delayed due to DirectX 11 support implementation. As Ralph Fulton said in a recent event in London:

"And that was a decision we took, to delay the PC version, to take advantage of DX11, purely because we weighed it up and said, look, what it allows us to do is make the best-looking racing game that has ever existed. Not just of the year or on PC, but has ever existed, because we were the first with an already cutting-edge game to take advantage of this technology, so it would definitely be worth putting it back."