Yeah, it's incredible. But AFAIK, it's not only cars, agents are everywhere in this game. If I recall correctly, latest SimCity also was focused on agents, but it seems Skylines devs are better ;). Good discussion: https://www.reddit.com/r/Games/comments/2rm5k2/cities_skylin...
SimCity used agents in places they're totally inappropriate though. Like power generation - that was simulated as agents which travelled along powerlines and jumped into the nearest empty building each tick.
Which of course utterly fails to capture any of the detail of an electrical grid.
