Cars on the road go too slow sometimes or break too fast and speed up too fast.
For example, I often see cars on the motorway going 25MPH, which is far too slow when the lane is clear for them to speed up and then sometimes they speed right back up to 70MPH, it's just unrealistic and ruins the experience. Furthermore, cars break too fast like going 70MPH then stopping then speeding up again. To add on, they also have this sudden slowing down then continuing speed action. Just to let you know, all my emergency situations are OFF and my traffic conditions are as follows in order:
60%
Fast Moving Traffic
60%