Driving Advice - Cordoba to Granada to Ronda and finish in Sevilla

I made a similar trip and loved it! The road system in Spain is first class and you should have no problems driving there. Since you're renting and returning the car in the same country, there should be no drop of fee. After you leave Ronda, consider driving through some of the picturesque white hill towns and through Arcos de la Frontera on your way to Seville - BUT be warned that those roads are twisty with a lot of elevation changes.

As Philip stated, the road system in Spain is very good and well marked. I always have a rental car in Spain since it affords the opportunity to stop where you want, when you want, and for as long as you want. Even when driving on the smaller roads you'll find them in a good state of repair. There may be more traffic and fewer lanes, but you'll get a better flavor of the country since they go straight through the small towns,rather than bypassing them on the autopista. I assume you'll be driving on some of them rather than the autopista for your trip. Once you have a rough itinerary, use google maps to get an idea of which roads you'll need to take to get there. Know which towns are along your route since the road numbers can change between provinces. In a pinch, look for the signs to the next town en route. When planning, if you think you may be confused in some spots, use the Google maps street view to view an interchange or the exit you'll need to take. Print out maps of your route and/or even your own written directions. I have a GPS loaded with European maps, but use it mainly to get me into and out of cities headed in the right direction. Driving and parking in cities can be a pain. If a newer hotel has a parking garage it should be fine to get into and out of, but the older hotels and parking garages were not built for today's cars. Most are very narrow and difficult to maneuver in. Parking in cities can cost as much as 20 euros a day. Back to your itinerary, once you have a route, do a little research (Flickr, TripAdvisor, etc.) on the towns along the way. You'd be surprised what some of those small towns have to offer. Then again, others are just small towns with nothing to offer. Last, ensure you get an international driving permit (get them at AAA) since one is required in Spain.

Cordoba
Granada
Nerja
Malaga
Ronda
Zahara/Grazalema
Arcos de la Frontera
Jerez
Sevilla

We just got home and did your exact itinerary:

We flew into Seville and took the bus to the train station and went directly to Cordoba.
Took train (with one train change) from Cordoba to Granada. However, it really went down like this: the first train went to Antequera, and the connection wasn't a train, it was a bus. They are doing construction, and so it is not possible to take a train. However, we purchased our tickets for the whole thing from Renfe.
Took "train" (i.e., bus to Antequera and then train to Ronda) from Granada to Ronda (again, tickets were all purchased from Renfe)
Took bus from Ronda to Seville - using the Los Amarillos bus company (we purchased our bus tickets at the bus station in Ronda)

Very easy. We were happy not to have any car rentals.