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being stationary and seeing a car reversing towards you. You can beep all you like but at some point moving away (which involves accelerating)
Doubt you'll need to go over the speed limit in this situation so it would make absolutely no difference if your car was limited.
In my own experience I've had someone overtaking me on a motorway blow a tyre
This is the kind of thing people are thinking of when they "need" the car to be able to go to 180mph for safety. Even though you may have come off worse with a limited car, overall people would be a lot safer. I'm sure with modern collision detection a limit could be briefly deactivated in an emergency, or maybe the occasional speed limit breaking boost could be an extra decent bit of power for a few seconds but everything that just happened is noted on a black box and uploaded to your insurers every time you "need" to break the speed limit.
That's kind of the point though. In some (very few) rare situations slowing down isn't necessarily the answer. (See how many caveats there were on that sentence...)
For example, contrived situation but quite common, being stationary and seeing a car reversing towards you. You can beep all you like but at some point moving away (which involves accelerating) is going to give you a chance of avoiding being hit. Do it in a panic and there's a good chance that you might end up hitting something/someone yourself.
Like most things, the answer is to do as much to avoid being in the situation in the first place (in this situation giving more room to the car in front) but sometimes even with the best judgement someone just does something so unexpected that you end up having to take avoiding action.
In my own experience I've had someone overtaking me on a motorway blow a tyre, swerve into the central reservation and then bounce off heading for me. In my split second WTF decision making I could have braked sharply (where I could either have been hit from behind by the person near tailgating me, or even by the careering car depending on how it's velocity changed post impact) or boot it into the clear lane ahead of me. I chose the latter and got away with it.
(The person tailgating me had been there for only a couple of seconds having pulled in behind me in order to overtake me. The lane to my left wasn't clear as I was overtaking someone myself.)