If you have parked over at the Guadalhorce lakes area by the start point of the Caminito del Rey then, once you finish your walk at Caminito del Rey, you can take the return bus (shuttle) service. (Approximately every 30 minutes.) The cost of the bus service is 2.50 Euros. However, make sure that you have the correct change as the drivers do not accept credit or debit cards. It’s also important to note that paying with a 100 or 50 euro note may cause some frustration to the drivers who run the bus services for the Caminito del Rey.
You could also park at the El Chorro area finish point and get the shuttle bus to the start point. That way your car is there when you finish the walk.