Sometimes people in the left lane get the idea that they have the right to regulate speed. They think they're going fast enough for anyone, if you want to go any faster, they're not going to move over and give you that choice. It's very irritating!
I remember some time ago, someone came up behind me and became very irritated at the speed I was passing a truck (so I couldn't get out of their way even if I wanted to). I imagined them becoming very angry at my 95hp K car, thinking I had no right being in the fast lane. In reality, I wanted to go faster too. It was the 911 Turbo in front of me that was going slow.

Sure, 115 is slower than 125.

In Sweden it's legal to pass on the right side if the speed limit is less then 90 km/h. It's illegal to pass if the speed limit is 90 or greater.

But they are not always "slow", they may be at 115 km/h and I pass them at 125

That´s why I think, we need these signs, too:

Not always. I do it in the same way. Often these idiots don't go right, they send some light-flashes behind me. It happened just last Tuesday to me again.

A few of them get the chance to make big eyes, when they will be stopped by the police and have to pay (not much 20 or 40 Euro or so). But this is the only way to learn, that this is indeed forbidden in Germany. It's forbidden to drive on the middle or left lane without any reason. You have to drive on the right lane, just for overtaking or if this lane is full, you can stay left. Many Germans have the wrong thought, that the right lane is only for trucks. This is a misunderstanding.

When a car is driving on middle lane on an empty road, I find funny to go from right lane to left lane, then go back to right lane after passing the car. And usually then the guy notice that he is alone on the road, and goes to the right lane

Technically it is here too, depending on the state, but it is not really enforced to hard so you can do it if you have to.

The yellow Kadett belongs to my Dad´s neighbor and is going to get the "H-Kennzeichen" soon.
Regarding the Audi, that guy (or gal) drove permanently on the left lane though there have been several opportunities to make way. Unlike in the U.S. it´s forbidden to surpass on the right lane in Germany.

I was going to ask if the unit on the dash was a pop-up NAV screen, but you used it (so you answers my question before I asked ... )

Those messages were funny, "Damn TDI won’t get out of our way "