Hmm what AA settings and sharpness settings are you running? I would try and experiment with that, maybe it helps.Does someone has an advice on the visual setting for Monitor? I have bit of trouble with the visuals in this game. It's hard for me to identify the Distance-Boards unless I'm really close and it's nearly too late to use em as brake markers :/
Also brake lights from the car ahead are nearly invisible at least when you have a Nissan or Ferrari in front of you. If they also have the lights on it's pretty much impossible to say if the brake lights are on or off.
For Brake Lights I would play around with Post Processing settings. This settings were responsible for the brake lights in the original AC, so maybe it is still like that.