It depends on the cim.
You have tourists that come into your city and their only job is to travel around your city all day until they spend their money.
Workers, however, like to get to work as quick as possible, as if they are late, they lose job and despawn back home to try to get to work again. The good thing is, that workers will walk to work if within 12-blocks of their home. so try to keep residential near jobs. If too far away, then they will pull out their pocket car and drive to work. If they can't make it, they despawn and try again.
I'm not sure the total length they'll drive, but it is based on time. so fast roads get them there the quickest. Traffic jams will stop them though. so always keep residential in walking distance to work. and your traffic should be low.