There is a report on another forum that these are now operating at Faro airport.

Apparently it has already caught offenders.

Anyone with an overstayed UK plate car should be carefull.

Hmm. This would only work if the database was kept up to date. Do you really think this is likely? I would be really surprised if they were able to do this but notwithstanding, it is probably best to have your car in the country legally rather than illegally!

So how does it work? Do they scan the foreign plate when it enters the long term parking and if the car is there for longer than 180 days they slap a fine on it??

If they are like the ones in the UK, they will be at the entrance to the airport and check as cars enter.

Like the congestion charge in London, the info is fed back to a database that checks reg no to see if payment has been made. or is the car legal ?
If not then a ticket follows.
So logically anyone without a valid road fund or " on the system " for any reason risks being flagged up.
It is also an aid to security.

How long are you allowed to keep a UK plated car in portugal for?

183 days max ? and then it has to be returned to its country of origin.

it goes without out saying that it must have a full mot, UK roadtax and insurance. ( unlike many you see around the Algarve , even in CVO )

Unless there is a link from the Portuguese to UK DVLA I can't see how this will work. How will they know which car is "on holiday" versus one that has "overstayed"? Neither will be on the Portuguese database. Sounds like scare tactics to me.

However, I have no time for illegal cars in any country as it normally means they are uninsured. Knowing somebody that was a victim in a death by dangerous driving by an uninsured person I fully support the UK approach of crushing uninsured cars. I'd be quite happy if they crushed the drivers as well!

One of the joys I get when driving in the UK in my little Dutch buggy is doing 70 in one of the many many roadworks on the motorways which limits you to 50

A N other

That is the thing - without access to the relevant databases, it won't work. Certainly not well enough to issue a ticket or summons - the best they can do is talk to the driver.

As far as I know there are no reciprocal arrangements with any other country for information stored on the DVLA database.

How it has worked up to now is that UK cars when spot checked are put on the GNR data base ( it has happened to friends , even when going through the matriculation process ).
When stopped again the GNR have a record so can easily see how long a vehicle has been in Portugal etc.

One aquaintance when stopped outside of the international school at villamoura was given 48hrs to remove the car from PT..

There is a move to make road traffic offences transferrable from one country to another , there are already reciprocal agreements in place.

The GNR have really stepped up their spotchecks, and are being totally anal about how they check you.
We have been stopped twice in the last week,

They blatantly accused us of having been here over the time and almost insisted we prove we hadnt been.

They check passport, driving licence, vehicle documents, UK taxation and insurance, AND your green fiscal card.
They stopped my wife, just between the Cespa filling station and Intermarche., last week, checked all these documents, then breathalysed her without reason.

There seems to be a permanently established check point for non Portuguese registered cars as you enter the airport. BE WARNED

I was stopped when I was over in December, but I´ve not been stopped on this visit yet. I´ve noticed there are many more roadblocks than there used to be though.

There is a reciprocal arrangement between Ireland, France and the UK. I guess it's only a matter of time before before the rest follow suit.

From the Horses mouth.
The reason there are so many road blocks and Police/GNR around is that due to the weather being so bad for the last 3 months with rain there revinew in fines is down by over 60% so orders from Lisbon are get fineing and stoping cars for any and all infractions, including minor ones, The officers also get a kind of commision, not in monetery ways but in extra days off and holidays.
All foreign cars are major targets, as long as your UK MOT is in date and your insurer is UK based your ok.
Hope this helps.

Hot stop spots are:

Before Cepsa garage
Lagoa roundabout
Vale de Milho /ADM crossroads
Salicos bend ( Side road to Lagoa past Fatacil)
Entrance to vale Centianes Beach
Carvoeiro Square
Roundabout between lagoa and sesmarias

You forgot one other very important thing CV1, and YOU HAVE NOT been in Portugal for more than 6 months.!!