i will be arriving in June, going straight to Toledo then want to visit Granada,Seville,Cordoba and Rhonda then return to Madrid , which order should it be? Will be staying 12 nights

Granada, Córdoba, Ronda, Seville? Return the car in Seville and take the train to Madrid. You don't have to take the expensive AVE one.

Are you flying in and out of Madrid? Sounds like a lot of places for only 12 nights. This past September we went to the same places (except went to Malaga instead of Ronda), but we had 15 nights. have your made your hotel reservations? How many nights are you staying in each place? I recommend deleting at least one destination, such as Ronda. I recommend taking trains because you don't need a car in the cities. If you do include Ronda, a car might be necessary unless there is train or bus service to Ronda. Train and bus service in Spain is excellent!

This was the order of our itinerary: Madrid, Toledo, Cordoba, Granada, Malaga, and then Seville. We flew home from Seville. Next time you should look into open jaw (or multi-city tickets) so you don't have to backtrack.

You don't need a car for any of these destinations, and the trains and buses are comfortable and convenient. In contrast, having a car in some of these destinations could be a hassle. Your call, of course....

Cordoba, Granada, Ronda, Seville.
Twelve night gives you enough time to either add Malaga or Merida.
The advantage of having a car is being able to explore the back roads and the countryside at your leisure.
Loop, don't backtrack.