DIS speed warnings

Been playing with the speed warnings on my A3, and am a tad confused.
Lets call the warnings S1 and S2 for brevity. If I set S1 to, say, 50mph whilst driving at that speed, then the warning doesn't seem to
trigger until I'm doing over 55mph(ish). The warning will then not clear until I drop below 50mph. I can understand the need for a 1 or 2mph difference between the "trigger" and "disable" points, to avoid constant on/off conditions whilst driving around the set speed, but 5mph!? If I set the speed warning at 50mph, then I want to know when I exceed that speed, not when I exceed 55! Is this normal or do I have a problem with mine?
S2 exhibits similar behaviour, but if I set this to, say, 80mph, then I seem to have to do around 90mph to trigger it!
My first reaction was that the DIS system was using the correct road speed, and the speedo was over-reading, as many of them do, but then the system should set the warning at whatever speed I'm doing, regardless of whether the speedo is accurate or not.
--
Toby

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AFAIK, it's normal. My A4 works the same way. I guess it has to do with the assumption that most cops will not give you a ticket if you're just a couple of mph over the limit, so the warning doesn't kick in either. If you want the warning to go off at 50mph, then set it at 45mph.
Cheers,
Pete
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writes

I suppose there's some logic in that, but the circa 10mph differential required at high speed is pushing things a bit.

Well there is that, but then if I stray over 50mph, I have to drop right down to 45mph to clear it. Does yours also do this?
--
Toby

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To tell you the truth, I don't remember, but my owner's manual says 'yes'. Apparently the warning also goes out if you drive 25mph above the set limit for at least 10 seconds.
Personally, I don't use these warnings because I find them incredibly annoying. ;-)
Cheers,
Pete
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writes

Heh :)
I mainly wanted to use S1 for watching speed limits, particularly temporary ones imposed on motorways and dual-carriageways, as in such conditions it's all too easy to stray over it.
--
Toby

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It depends on how *fast* you're getting to the given speed. (i.e. acceleration seems to pay a major role)
It's not an accurate way to see what you're doing with Gatsos...
--

Regards,

Hairy One Kenobi
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Interesting, not realised that, will have to experiment.

Heh, you read my mind :)
It's the 40/50 limits at motorway roadworks and such like where I need it most, as it's very easy to stray over the limit. I'm currently using the cruise control to maintain a constant speed in these circumstances, which works quite well.
--
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