As far as I know here in the states the outside lane is for passing, the center is known as the Travel lane and inside is the slow vehicle lane. Now if you are slower than a car in the travel lane, you get out of it to the inside that car should not have to go to the passing lane to get around you if there is an open inside lane. If you are the only one on the road you are the slow vehicle and therefore suposed to be on the inside lane. But then when in heavy traffic I'm not going to jam on my brakes in the outside lane just because the "Passing Lane" has come to a crawl. Now the four laners are a different story I'd guess!