A foreign car in Spain, no Spanish plates

"Even what you in the UK call the MOT, the Dutch version of it, can be done in the south of Spain!"

In Spain called an ITV, but the car needs to be on Spanish number plates.

Thank you for your reply! So as a non resident, with a NIE number and an address in Spain it is not possible to have a car in Spain?

Hi.  Once you complete your property purchase, you need to register on the padrón at your local town hall.  Once you have the document showing you are on the padrón, you can buy and register a Spanish car.  

We are in the same situation as you with cars in Spain. As non residents. You are right about the prices of second hand cars here 3 times dearer than the UK prices, we decided all the hassle  not worth it about having a car six months here. Also with UK plates here you are stopped by the police more just so they can pass the time.
My personal experience only 

I've had no problem buying a (new) Spanish car in San Pedro and I'm not resident. Just needed an NIE and my Spanish address. Insured locally with op de Beeck & Worth, who were excellent. You can tax it online easily.

I bought my car in the UK, a LHD model and drove it to Spain. Gained my NIE and registered the car here. Have the ITV as well. Just paid a solicitor to do it on my behalf. Cost less than 200 Euros and the car is still great value compared to prices in Spain.

"I bought my car in the UK, a LHD model and drove it to Spain. Gained my NIE and registered the car here. Have the ITV as well. Just paid a solicitor to do it on my behalf. Cost less than 200 Euros and the car is still great value compared to prices in Spain"

 Was that while still an EU citizen & you swaped your licence OK. How about things like changing the lights?

He brought a left hand drive model, no changes needed.

Indeed with a LHD no changes needed, but he never answered if still while an EU citizen post Brexit.