Why aren't cars fitted with speed limit reminder systems?

Among the myriad of gadgets in modern vehicles, I wonder why there is no "Speed Limit Reminder". As you enter the speed limit you would press the appropriate one of a row of buttons on the steering wheel, marked "20", "30", "40", "50", "60" and "70" mph. If your vehicle exceeds the set speed, a buzzer would sound every few seconds as a reminder. I do try to obey speed limits and any speeding is due to forgetfulness or inattention - a reminder would help enormously.

Asked on 9 January 2012 by JW, Chester

Answered by Honest John
There is. It is a camera system fitted to new Fords and GM cars (among others) that recognises road signs and posts a reminder in the driver's view. There's a bit about it in the Focus video test here: www.honestjohn.co.uk/road-tests/ford/ford-focus-20.../

Other systems use GPS satnav to remind the driver when he is in a limit, but this is less reliable because the mapping it is based on could be out of date.
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