I imported my motorcycle into Spain. You will need to obtain an NIE (numero identificad extranjero) in order to permanently import your auto into Spain. NOTE: In Alicante, I was sent to the Elche Policia Nacional office, then sent to Elda, back to Alicante. I gave up, called my mortgage broker, who then sent me to Denia, where I got my NIE application in. It will take you about 30 days to receive it back. In order to get an NIE, you will need to have purchased real estate, or have a rental contract.
If you purchase a car in spain, you will also need an NIE, or someone with a DNI to purchase it for you. Without one, its impossible to buy a car here. The taxes are always included in the price. If you buy one in Germany, you will need to own it 6 months prior to import AND have a certain number of miles AND provide proof that you paid taxes in the country of purchase.
If you do not permanently import your car, the aduana stamp is good for 180 days. Hope this helps. 😊