Most Rental Car companies require a Credit Card on arrival. The security deposit is ¨held¨ on the card and not withdrawn, for the duration of the hire and released when the car is returned without any claims or damages. Credit Cards provide a higher level of security for the rental car supplier, as opposed to a Debit Card.
Some rental car companies like GOLDCAR will accept a Debit Card but you must have enough ¨credit¨ on the Debit Card to cover the Excess insurance amount. This Excess amount can vary wildly between 300-3000€ in certain countries. The Excess amount will be withdrawn from your debit card when you arrive. Look under: "IMPORTANT INFORMATION" then choose tab "DEPOSIT".
Some of the car rental providers in Spain who accept debit cards to hold the security deposit are:
AUTOCLICK,
CENTAURO,
DRIVALIA,
GOLDCAR,
OK Rent a Car,
PULSAR Car,
RECORDGO,
RHODIUM,
VICTORIA Cars