It is now obligatory to have an NIE (Numero de Identidad Extranjero) when purchasing a property in Andalucia. For EU citizens, the application can be done very easily by a visit to the corresponding National Police Station (Comisaria). You will need a completed NIE application form , the corresponding completed fee payment form (which need to be collected from the police station before the application and the aprox fee of 16€ paid at local bank). On the day of application you may need to visit the Police station very early in the morning on the day of application in order to acquire a number for a place in the queue! Once you return for the application with completed NIE form (1 original & 1 copy), stamped fee form with proof of payment, & good quality copy of passport,the application is processed fairly quickly and your new NIE number should be return to collect in 3-4 working days.
With this NIE number you can now purchase a property, a car and open a bank account.
NOTE: In addition to the above, Non EU buyers may have to present proof of property reservation as well as proof of their arrival to Spain i.e copy of airline ticket.