4x4 in Spain are classed as commercial vehicles and as such cannot be replated from UK to Spanish plates, so don’t buy them.
Also a Japanese cars with UK plates cannot be re-plated as there chassis numbers are too long and don’t get accepted into the system, a friend did this a found out after the Guardia pulled him, so he went and got the lights changed etc which cost around 800 Euros, but it could not be ITV or re-plated.
So he had to scrap it as if he drove through Spain back to the UK and got pulled by Traffico they would have gone ape with fines etc.
Stay well away from UK plated cars.