If you usually drive at 90km/h in the fast lane of an expressway because you find that traffic there is smoother, chances are you’ve encountered other road users flashing their high beams at you.
There are traffic regulations and there is road etiquette.
Although you are not breaking any traffic regulation by moving at 90km/h on the right lane of an expressway, you are holding up others who may wish to overtake.
This can be frustrating to others – especially if the distance between you and the vehicle in front is vast.
You may think the motorist behind you can overtake you if he is in a hurry, but strictly speaking, overtaking on the left is not allowed.
So, to do the right thing, stay away from the right lane if you intend to keep to 90km/h. But, of course, if traffic is heavy all round, it is fine to use the right lane – even if your speed is below 90km/h.