Joining a little late on this one...
So I could read the rest of the posts, but in the interest of saving time I'll guess at the content of some of them and answer them as best as I can.
"Big Brother is watching you! 1984! Orwell wrote it as a warning, not a manual!"
Shut up. Excessive speed is the number one contributor to road traffic accidents. That's not breaking the speed limit, but speed in excess of what is safe for the conditions. When the public can be trusted to drive defensively without this kind of draconian enforcement, I'll be right behind them screaming for its abolishment.
"Why can't the car just be limited to the speed limit?"
Good question. By way of an answer, allow me to cite a few names:
All manufacturers who sell cars boasting about the top speed. Can you put that 200MPH SLK Black on the motorway and get anywhere faster than a Ford Fiesta? No. 70MPH is the limit. Whether that is just, sensible, or valid or not is not up for discussion here. Exceeding the speed limit is illegal. Look to these manufacturers for why cars aren't limited.
"But cutting the throttle during overtaking will be dangerous!"
No. Your driving is dangerous. Yes, you can wait behind that little old lady tottering down the country lane at 40MPH. You do not need to do the speed limit; It is not a target. Good progress is always preferred, but I bet those of you whining about this thing cutting your throttle at the speed limit try and overtake a Punto doing 50MPH on a country lane in the wet. Nobody puts you in a dangerous situation except yourself, so don't go blaming technology for your lack of care.
Did I miss anything?