As previously mentioned, unless you are extremely wealthy (and old school) or a major president of a corporation, it is unlikely that anyone will be driving you around other than yourself!
The economic crisis has made hiring a car a little more difficult in the tourist season, as car rental companies are selling off their fleet due to slumping tourism projections and raising prices on the remaining cars. If, however, you arrive outside of peak season, and/or are not picking up your car from one of the major airports, you will probably not notice any major difference in the way your rental enquiry is handled or processed. Please note that most car companies are renting manual or stick shift. If you are looking to rent an automatic car, your costs will significantly increase.
The major car hire companies operating in Spain are:
The major companies will charge you an average of €70 per day. For a local option that is more economical, try Pepe Car (http://www.pepecar.com/en/index_new.html) Rates start from only €15 per day, but average around €50 per day. You can also try Victoria Cars (http://www.victoriacars.com/) with an average rental rate at about €60 per day.