General Driving rules in Portugal

Driving age in Portugal is 18 years old
Driving in on the right side with the wheel on the left side of the vehicle
Portugal drink drive limit is 0.5 grams per liter of blood, with lower limit 0.2 for some drivers. EU standard. Severe fines for drunk driving.
Use of cell phone - you can use only with hand-free system
Headphones are illegal
Seatbelts are compulsory for driver and passenger
It is illegal to overtake on the right in free-flowing traffic
In case of accident - Police number: 112


 Speed Limits in Portugal

Speed limits are indicated on circular signs with red border and a number
Speed limits are in kilometers per hour
National speed limits are - 50km/h in residential ares, 90km/h on rural roads and 120km/h on Motorways
Car towing trailers should not drive above 80km/H
Circle blue sign with numbers indicate minimum speed on some lanes

Roundabouts in Portugal

The law in Portugal for driving on roundabouts is not like the law in many other countries:
When you enter a roundabout, always give way to traffic already on the roundabout (approaching from the left).
If the roundabout only has one lane, things are simple. Enter the roundabout then take the exit you want to.
For roundabouts with more than one lane:
If you want to take the first exit from a roundabout, keep to the right-hand lane as you approach the roundabout. Otherwise move to the left-hand lane as you approach the roundabout then move to an inside lane on the roundabout.
Stay on an inside lane on the roundabout until you approach the exit you want to take. Then move to the outside lane and take the exit.
You are breaking the law if you are on an outside lane on a roundabout and pass an exit without taking it.
Be very careful with slow-moving traffic (for example, a heavy goods vehicle) driving on the outside lane of a roundabout. If you are on an inside lane and there is any doubt about taking an exit, simply go round the roundabout again.

Toll roads in Portugal

Portuguese Motorways are not free. They have tolls along them.
When you rent a car in Portugal your rental car will come with a transponder for automatic payment of the highways each time to go through a toll. At the end of your contract you will pay at the agency the balance. 

License to drive in Portugal

If you are from the EU and have a valid license from your own county with picture then you can drive in Portugal
Coming from another country you will need to have both your license and the International Driving Permit - You will be asked by officials and rental agency;
The law allows you to drive from 18 years old but most rental company will have other requirements such as being 21 years old or 5 years of having a driving license... Check with each rental agency.

UK drivers driving in Portugal after Brexit

The good news is You do not need an International Driving Permit (IDP) to drive n Portugal unless the UK leaves the EU without a deal and you’re staying for more than 185 days.

In the event of no-deal, what will I need if I take my car abroad?
In addition to your UK driving licence, motorists may also be required to purchase an International Driving Permit (IDP).

There are three types of IDPs available, though only two are used in EU states and European Economic Area countries.

Which IDP will I require?
1949 IDP: If you are travelling to Ireland, Malta, Spain or Cyprus, you may require a 1949 IDP. The 1949 convention IDP is valid for 12 months.
1968 IDP: If you are travelling to all other EU states, you may require a 1968 IDP. The 1968 convention IDP is valid for three years, or for however long your driving licence is valid, if that date is earlier.
1926 IDP: A 1926 IDP is not required in any EU state. However, it is required it if you plan to drive in Mexico or Somalia. You may need a 1926 IDP to drive in Liechtenstein if there is no EU Exit deal
For further details on countries' IDP requirements visit the Government website.

To drive in Portugal the 1968 IDP is the one required. However you do not need an IDP unless the UK leaves the EU without a deal and you’re staying for more than 185 days. If you have an older, paper UK driving licence, you must take another form of photographic ID, such as your passport.


What to do if you are involved in a traffic accident in Portugal

Traffic accident in Portugal ? Stay calm. Police and insurance companies will deal with it. Use safety equipment, get driver and vehicle details. Call 112.
Call the Emergency services

If anyone has suffered death or an injury, you must by law wait at the scene of the accident for a Portuguese agent of authority to arrive. If you fail to do that, you incur a fine of €500-€2500 if not more. Call the emergency services number 112 and they will notify the police and possibly the ambulance service. You can expect the 112 operator to speak good English and be well-trained. Stay calm and answer all the questions the operator may ask.