Hi, I bought a UK vehicle and brought it over.
( I did used to rent but I had a jetski and I need a vehicle with a tow bar, which is not easy to rent with)
I changed the headlamps ( ebay... Left hand drive replacements) and had my solicitor do the rest. It did cost about 1000 euro to change but I only paid £2000 for the car. ( freelander )
I leave the car at airport ( one of the parking companies will transfer your car to either Murcia or Alicante if you let them know).
All what John has written is correct but I am glad now to have the car in Spain and once done its great. The costs are not too high and I drive appx 3 - 4000 miles a year .
If ( as John has said ) you only come irregular and for not a long period then hiring is best especially as Condado club hire is cheaper now. ( was a time in Summer when car hire was a few hundred a week)
So yes duty is a big cost as a one off hit but if you factor all of it in ( including no queues at the airport) I am happy with my choice to buy second hand Uk and bring over.
Insurance is direct line ( Spanish )
Mot ( TUV) is only 40 euro a year.
Hope this softens johns factual post.
( nothing wrong in your post John other than matter of fact. Please do not take offence non is meant)
Cheers
Neil