Spanish car rental has two traps that cost money after the car is already returned. Both are avoidable and both catch people every year.
The fuel policy
Full-to-full is the one to take. Collect and return with a full tank, paying only for what you use.
Full-to-empty charges you for a full tank at an inflated rate plus a service fee, and you cannot recover the value of whatever you leave in it. Returning a car half full means paying for fuel you gave back.
These policies are frequently attached to the cheapest headline rates, which is how they pay for themselves.
Photograph the fuel gauge at pickup and return, and keep the final receipt from a station near the airport.
The zone fines
Spanish cities above a certain size have low-emission zones with camera enforcement.
Fines are issued automatically and passed to you by the rental company months later, with an administration fee.
Seville, Madrid, Barcelona, Málaga, Córdoba and Granada all have restrictions of some form, and the boundaries change.
Park outside the centre and walk in. Underground car parks on the edge of old towns are the standard solution.
The same applies to bus lanes and pedestrianised streets, which are also camera-enforced.
Insurance
The base rate usually includes cover with a substantial excess, and the desk will offer to reduce it at a high daily rate.
Independent excess insurance bought separately is generally far cheaper — it works by reimbursement, so the deposit hold on your card still happens and you claim afterwards.
Check whether your credit card provides cover, and read what it excludes: tyres, glass, undercarriage and roof are commonly out.
A large deposit hold is placed on a credit card and released after return. Debit cards are frequently not accepted for this.
At pickup
Photograph everything — all four corners, the roof, the wheels, the windscreen, the interior, and the fuel gauge.
Check existing damage is marked on the form before signing.
Confirm the transmission. Manual is the default in Spain and automatics cost more and must be booked specifically.
Check for a Crit'Air-equivalent or zone sticker if crossing into France.
Tolls
Some Spanish motorways are tolled — routes prefixed AP were traditionally the paid ones, though several have been converted to free roads in recent years.
Free A-road alternatives usually parallel them, are slower, and are frequently perfectly good.
Check the current status of specific routes rather than assuming from older information.
Driving practicalities
Speed cameras are numerous and fines are enforced across the EU.
Drink-driving limits are lower than in some countries and are strictly enforced, which matters in wine regions.
Village streets are narrow in Andalusia and the north — a small car is genuinely easier.
Fuel at supermarket stations is cheapest; some are unattended and card-only outside hours.
Rural stations may close at lunch and on Sundays.
Where to rent
At regional airports — Málaga, Seville, Bilbao, Valencia — rather than city centres, where returning a car involves the zones.
Book early for summer; Spanish fleets run out in August and prices climb sharply.