Using either of the 2 account heads does not make much differnece since both are indirect expenses, but using both the accounts alternatively for the same nature of transaction is an incorrect practice. They should use any one account consistently. conceptually, as Sumit has clarified, Motor Car Exp A/c should be used when own car is used and Car Hire Charges (not just Hire charges) used when a hired car is used. But use of any one of the 2 accounts can be accepted if consistency is maintained.
The hotel can also take a view that hired cars are direct expenses since they are directly used for providing service to customers and can treat accordingly. This classification should be determined thoughtfully and followed consistently since that affects gross profit. Here, argument that both are debited to P & L will not be valid.