Anyone who becomes a resident in Portugal is eligible to import one foreign-registered car tax-free. This is good news because the import taxes on cars here is extortionate, however, you do need to work through a whole list of documents and meet certain criteria in order to comply with the tax-free status—and you must have owned the vehicle for more than 6 months.

Coming from Spain, my little car had Spanish plates, but the same rules apply to importing vehicles from other EU countries and also British or US registered cars.