Having no general speed limit needs to be a thing of the past. The speed difference between people who wanna drive economically and safely and those who want to put the pedal to the floor is just too big. It may have worked in the 50's to the 80's where fast cars were the exception, but nowadays virtuall every family sedan is capable of reaching 180 km/h or more. If you're going a leisurely 100-120 and someone is doing a low level flight at at least double your speed, things get dangerous. Traffic density simply doesn't allow that idiocy anymore.
Even if there is no speed limit, there is a guideline speed of 130 kmh and the right-hand driving rule. If the rules are adhered to, you only overtake in one of the left lanes (whereby you must first check whether the lane is free) and then back again. It is not a big problem if you are overtaken with a speed difference of 200 kmh.
Of course, the speed must be selected according to the traffic situation, which means that you are only on the road at high speeds when the highway is clear.
With 180-200km/h delta you couldn't possibly judge the traffic situation, let alone react in time. I think you meant 100km/h difference, right?
But even with a delta of "only" 100km/h the distance between cars shrinks by about 30m per seconds. Even with optimal visibility and full attention on the road this gives you a couple seconds at best to correctly assess the situation. Then you can only punch the brakes and hope you remain in controll over your vehicle.
Imho there is no justification to allow PKW move that fast. At those speeds you not only your life but that of others as well.
And i haven't even touched on the environmental impact and fuel efficiency of high speeds.
I've learned that with a distance of 2 seconds you have always the right distance to the other car, independent with which speed. That is easier as to calculate the meters, enogh to look when the car in front passes some mark (post, tree, some sign...), count 21 ..22. When you then pass this mark, you have a distance that allows you to stop safely.
It makes a difference if there is an unlimited section, I start to overtake someone with my weak base engine VW Golf and accelerate to 130 to complete my pass. And then a BMW/Audi/Mercedes approaches at 200+, flashing his high beams barely two car lengths behind me. I'm by no means an insecure driver, it just drives me mad. Some people think that just because an unlimited section of the Autobahn has started, everybody needs to move out of their way immediately or take part in a top speed chase with them. The sense of entitlement is strong out there.
At which speed would I be allowed to use the left lane to overtake someone on the Autobahn, then? Somewhere north of 180? I'm assuming you have vast experience on the German highway system, so please do let me know.
When there is nobody driving that fast behind you in the left lane. I assume you look into your mirrors before switching lanes...? If so, whats the issue with people going faster occasionally on the left lane?