Vehicle Registration – foreign cars
Many people who stay in Spain permanently and still use their UK registered vehicles do so against the law. You should either, import the vehicle and change to Spanish number plates or it may be assumed that as a non-resident you intend returning to the UK in order to maintain the tax and MOT requirements. You do not have to be a resident to import a vehicle, but if you do become resident, it is then a legal requirement to do so within six months of obtaining the vehicle.

Motorcycles and Mopeds
If you hold a full UK driving licence and you are not a resident of Spain, you are allowed to drive a motorcycle or moped up to the cubic capacity shown on your driving licence. 

All motorcycles and mopeds, whether Spanish or UK registered, should have a current road tax. It is true to say that many foreigners living in Spain pay lip service to maintaining their UK tax, but you can be fined if you are stopped and fail to produce valid documents.

Vehicle Insurance
All vehicles using the roads in Spain must by law, be fully insured for third party damage including medical cover to enable anyone injured in an accident to be taken to the nearest hospital.

Many companies accept a no-claims discount of up to 60 percent providing you can provide a certificate of proof from your previous UK insurers.   Motor insurance is now widely available.
 
Driving Licences
If you are a resident of Spain and drive a Spanish registered vehicle then strictly speaking you should have a Spanish driving licence.

Any valid EEC driving licence is legal and acceptable in Spain. The bottom line is if you own a Spanish registered car, you are resident in Spain and therefore you should have applied for your residence permit and then presented your licence for inspection and stamping or exchanged it for a Spanish licence.  If you are not a resident and drive a Spanish vehicle you may have to prove your status. To do this you need to obtain a Certificate of Non-Residence to carry with your UK driving licence.

Given the levels of bureaucracy and legal issues associated with motoring in Spain, it is advisable to use the services of a “gestor”, an advisor in all bureaucratic matters.