Because Piran is very small and has narrow winding streets, only the local cars are allowed to drive in town and visiting cars will need to park outside town at a big parking lot.
From there you do have a free shuttle bus, so things are really good there and you avoid traffic congestion in the old town.
The bus is a white minibus with a blue and red strips on it and it leaves every 15 minutes from the town entrance and from the main square.
The ride is free and it takes 5 minutes and helps to make Piran a much more attractive town.
There's a free shuttle that runs between the main parking and the center. As the traffic is very limited in the old town, there is a parking fee inthere. It costs 150 SIT onwards, depending how long you stay in town.
The best way to visit the old town is on foot