So, we have one vacant place and 4 occupied places. If you mean circular permutations, then we may assume that the vacant place is in position "North", or "12 o'clock". Then 4 other positions are occupied by 4 cars, and we should calculate the number of placements of 4 objects in 4 positions. It is precisely the number of permutations of 4 objects, which is 4! = 24. ANSWER.