Hi There is no blur effect through windows in cars as Bentley Continental or McLaren 650S. With Callaway and Mercedes it seems to be ok. I haven't checked in Radical RXC or other S397 cars. I have played with the focus of camera with different cars, but seems to be a bug in some cars. McLaren in Malaysia v1.7 from S397 Bentley in Road America DX11 v1.4 from Shiet. And an example of other cars that seem to be ok, as Callaway, also in Malaysia v1.7 from S397:
And this is without S397 skin, but is the same bug as in Malaysia v1.7 with original S397 skin, there is no post-processing effect through windows. In Oulton Park DX11 from Digga (odb's workshop):