Southern California does have some toll roads that charge automatically to the car driving in them. Most rental cars have a "fastpass" device attached to the front windshield which you can flip open so that the toll roads can read the car and assess the correct fee. You just have to flip it open (Note that if you don't open the fast pass and you use a toll road, you may be assessed a penalty fee much higher than the actual toll which is usually $1-3. Important to note however, is that toll roads are not mandatory. Most of them are on the major freeways and act as a "fast lane" in the center of the freeway. If there is traffic you can pay a toll and get into the fast lane and bypass the traffic. There are a couple segments of freeways which are completely toll roads (all lanes) but there are alternative routes that you can take to avoid having to pay the toll on public roads.