Yes, of course it is, to keep the car there legally. But a new law from January 2009 requires that only Spanish residents can register cars in Spain, so you have to decide whether to establish your residency there or not. More in "Motoring in Spain” THIRD EDITION (ISBN No. 978-84-611-9278-6), by Brian J Deller. More at www.spainvia.com/motoringinspain.htm