This is just a little dumb suggestion but you should consider stepping up the pathfinding for the vehicles, Iv been seeing that if you place two roads one next to each other they will just take the nearest one making one full and the other one empty, that could be a long-term problem with big developed cities.
It would be a good idea to make the AI evenly distribute themselves along the different paths to wherever they are going.
Iv also seen that as a solution cars that seem to not move for a long time or that get run over by other cars they will just despawn, it is a nice solution, but over time when the player already has a big city with a stable economy he might just stop building and start looking over the beautifully city he made, and then he notices cars eating each other.
It is funny to watch, don't get me wrong, it's just that little details would make the game more fun!
Better car AI?
it's fixed
It was like that and I have a massive city and before the update I had to have triple lane roads (still have them) but the traffic is so much better as now there is no traffic jams (40,000 residents in 1/4 of huge map yes it's that big)