It’d be nice if traffic could honk their horns if they are blocked, cut off, or an oncoming vehicle enters their lane. Just a little extra detail to increase the immersion a little bit when you’re out in free roam or street racing.
Accompanying them flashing their lights. As long as it can also be turned of I do like the idea in general. You should want to have the traffic use quite a number of different horns and not just one or a few. It could get an annoyance real quickly then.