Renting a car in Spain is not cheapest of all options available but it is surely the most convenient method of travel. The basic of car rental may cost more then a bus ticket or train along with what you invest in petrol and road tolls but it is essential if you want to explore the Spanish cities to depth, especially if you're planning to travel hard to reach regions such as Ras Bajas, Alpujarras or three surrounding Tarifa and Cadiz.
It is important to have an international driving permit or an international driver's license in order to rent a car in Spain. International driving permit is basically a certificate that authorizes driver to drive anywhere in the world and verifies that the driver license is not forged. You can get your driving license translated to multiple Spanish languages so that officers of different regions can identify your information. This is only possible if you have an international driving permit and the certificate is slightly larger in size than standard driver's license. The certificate is generally issued for a year.
Make sure that you qualify minimum requirements for car rental in Spain. You have to be over 21 years of age with a passport and a major credit card (MasterCard, Visa or American Express). All this will be required when you pick up the vehicle.
You can visit websites of various travel companies such as Expedia, Travelocity etc. which can arrange car reservations for you. The rental charges get automatically converted into your country's currency. This way you'll be easily able to understand the costing. You can also go directly to car rental corporations that have international service such as Europcar, Hertz, Budget, Alamo or Avis. These companies arrange car rental services inside Spain over the phone.
There are a lot of car rental agencies which would allow you to allocate flyer miles in turn of car rental. You can also ask for loyalty discounts. You'll need to select the dates of when you would want the car to pick you up and drop you at locations. A lot of people choose to be picked at the airport for convenience.
Making reservations for airline, accommodation rental and car rental at the same time is always convenient and will help you in easy correlation. Make sure that you have all the relevant paperwork that is required in Spain such as proof of insurance (need to be provided by car rental company) etc.