Another point to note:
When you drive across the border into Spain from another EU country of residence you cannot prove date of entry unless border contrl, stamps your passport. Diesel or petrol receipts are not acceptable. You ahve to make an appointment at the British consulate in Barcelona and you have to appear in person now and make a solemn oath andit costs in the region of 157 euros! But you do not get this document that Trafiko needs  on the same day. It takes the British authorities over a week (if they are not busy!) to fwd this document to Trafiko.  They will not accept emails from the consulate to say you have done -they need the document or you pay the tax!!

Nightmare! :o