[glenneroo]

I believe this is true in most of Europe - stay to the right except when passing, which you do on the left.

On the other hand, some cities (such as LA) have off-ramps on both the left and right sides, not to mention many multi-lane freeway interchanges located on both sides... combined with Google Maps telling you at the last minute that you need to be in the left 3 lanes, followed by immediately being in the right-most lane in order to get on the right freeway. Almost every visit to LA requires 1 or 2 retries on a few of these freeways. When I'm not constrained for time, I often opt for much slower side streets to avoid the utter insanity of some interchanges.