I think the streetcars are the most realistic UF 1000, XF GTI, XR GT, XR GT TURBO, RB4 GT, FXO TURBO feels natural.
With all the other cars i feel less connected. I don't think the open wheelers are realistic or the GTR's for that matter. But i am not a racer in real life, so i am just speculating. I guess netkar pro is more realistic compared to open wheelers in lfs.