Foreign vehicles can be driven in Spain for a total period of six months (or sometimes only two months, depending on the situation of the owner) providing the car is totally legal on the road according to the laws of the home country.
-This means that it needs to have a valid roadworthy test (MoT, in the case of British-registered cars), but what do you do when it expires?
-There are two correct options. The first is to take it back to your country of origin and pass the test there. Or you can begin the process of re-registering your vehicle in Spain. As part of this, the vehicle has to pass the ITV “para matriculacion” test which costs more than 100 euros.
Please be aware that the ‘normal’ ITV process, costing around 50 euros, does not apply in this situation, although most ITV stations may let you waste your money while knowing that the normal test is not relevant on a foreign-plated car.
 In these circumstances, if you are stopped by police and show a ‘normal’ ITV certificate, far from appearing to be obeying the law, you could be giving them the excuse to impound your car.
This is because by having taken the ITV test, you are implying that you do not intend to have the vehicle re-tested in your home country. Therefore, it should have been re-registered – and passed the ‘para matriculacion’ test – here, so you are technically breaking the law and ignorance is rarely an excuse.
 In addition to having your vehicle taken away, you could also be liable to pay the importation tax immediately.  
 If you are at all unsure of the correct procedure, always consult accredited specialists in Spanish motoring law.

By M.E Express