A reliable car is an important asset whilst serving in Portugal, particularly if you want to see something of the country. However, Portuguese roads are far from the best in Europe and the standard of driving/accident rate is the worst or very near it. Defensive driving is very much the order of the day.
In addition wear and tear on vehicles, due to poor standards of road construction and maintenance is significantly higher than in the UK and servicing costs and parts are higher too in Portugal. Thus bringing a brand new car to Portugal at the beginning of your tour is not recommended. It is preferable to bring an older car that you can try and sell when you leave to go home before the end of your tour to purchase a tax free car.
Alternatively, you can purchase a vehicle (free from Portuguese tax) from within the local NATO community - there are normally a few second hand left and right hand drive cars available: known locally as "Iberwrecks" most have seen some good service and the small market means they are slightly more expensive than you might expect but it does save the cost and hassle of bringing a car out from UK.
We can only speak from our own experience, but tax-free cars which have been used by British Forces in Portugal and then traded in against a new car in the UK are certainly no worse than cars returning from other countries. If you want to risk driving your family around Europe in an “Iberwreck”, it’s your choice. Many of our British Forces customers based in Portugal swap cars every six months, which they are currently permitted to do, as opposed to every year as in BFG. This enables British Forces in Portugal to really benefit from the big discounts and tax savings on offer, when buying a new, tax-free car.