Solution: This problem is a geometric concept problem. Suppose is the time when A and B arrive respectively, and is the probability that A and B ride in the same car. When waiting for at most one car, there are situations in which A and B ride in the same car.
　　(1) A and B get on the same bus as soon as they see the bus. The situation of getting on the bus as soon as they see the bus is as shown in (a).

;

(2) A arrives first and waits for a car, and rides the same car with B, as shown in Figure (b), then

;

(3) B arrives first, waits for a car, and rides the same car with A , the graph is similar to (b), and the probability is equal to .

　　To sum up, the required probability is

.