The same effect was observed in Poland, when the speed limit on the motorways was increased to the highest in Europe(140km/h, or about 90mph). Vast majority of people on the motorways don't drive at the limit, because most cars are just not comfortable at this speed. If you drive a modern MB or Audi that is designed for cruising at 90mph - sure, that works. But a 1.2L Civic? It's really loud and not stable at all at those speeds. So whenever I drive in Poland, even just doing the limit, not above, I overtake almost everyone in the right lane. Obviously, there are still people going much quicker than the limit(200km/h or 120mph is not uncommon) but in general it got rid of the issue of people sitting right at the limit or slightly above it, at least on the motorways.