To find out how many students were in each bus, we first need to determine how many students rode the buses.
We know that 4 students rode in cars, and the total number of students is 472. Therefore, the number of students who took the buses is:
\[ 472 - 4 = 468 \]
Next, since these 468 students filled 9 buses, we can find the number of students in each bus by dividing the total number of bus riders by the number of buses:
\[ \frac{468}{9} = 52 \]
Thus, each bus had 52 students. The answer is:
52 students.