Are slow drivers getting slower?

[Supercharged]

Are slow drivers getting slower? I have noticed that since the 50km/h for suburban areas came in some time ago many drivers in the noddy type of cars now travel at 50 and less in 60 and 70 km/h areas holding up the traffic flow more so than before and getting worse.
Out on the open roads they seem perfectly happy to travel at 60 or 70 in 100km/h zones and they often travel in packs requiring me to overtake 2 or more in one go travelling too close to allow another vehicle to overtake one at a time as they don’t leave enough room between them.
They travel so slowly that I wonder if they are driving with one eye on their litres per 100 kilometres to minimize their fuel usage with little regard for other road users.
The thing I find strange is if I am in the Falcon or Ranger they don’t pull to the left and let following drivers go even when the road side allows but when I am on the bike solo or more so in a group of bikes they just about jump out of the way to let you past.
I don’t drive as fast as I used to and now rarely exceed the speed limit but the amount of these slow drivers I come across in even the Ranger which is no sports car seem to me to be increasing.