Renault Megane - Incorrect dashboard speed limit display

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Wed 5 Dec 2018 22:07
Renault Megane - Incorrect dashboard speed limit display - Ian_SW

I'm driving around this week in a hired Renault Megane. It's better than expected, but I don't know how they've managed to make the (very large) speed limit display on the dashboard so innaccurate.

So far, it has:

1) Told me on multiple occasions that I'm in a 50mph limit when the speed limit is 30mph

2) Told me several speed limits are 30mph despite them actually being either 40 or 50

3) Tells me that the speed limit on a NSL single carriageway local to me is 40, when I know it's not been anything but NSL for at least ten years and is well signposted.

3) Repeatedly informs me that the national speed limit on a dual carriageway is 60mph

I've been trying to decide how the system works. At first I thought it was getting speed limits from an out of date satnav map. However, it does seem to get some temporary roadworks limits correct so it must be using either a camera or some form of map which is updated regularly. Surely with a camera system, if it can't accurately decide what the limit is due to dirt on the sign/camera etc. , it should display nothing rather than display something incorrect.

I've never come across such innaccuracies on similar displays on other cars, what are other people's experience?

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Wed 5 Dec 2018 22:27
Renault Megane - Incorrect dashboard speed limit display - SLO76
It’s French, just be thankful it starts In the first place.
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Thu 6 Dec 2018 09:22
Renault Megane - Incorrect dashboard speed limit display - TheGentlemanThug
It’s French, just be thankful it starts In the first place.

Aww, I was gonna say that.

In all seriousness though, it's just another example of change for the sake of change. Innovation that adds nothing when far more important issues should be tackled.

Edited by Bicycle_Repair_Man on 06/12/2018 at 09:24

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Wed 5 Dec 2018 23:05
Renault Megane - Incorrect dashboard speed limit display - Andrew-T

Surely with a camera system, if it can't accurately decide what the limit is due to dirt on the sign/camera etc. , it should display nothing rather than display something incorrect.

If it can't recognise the sign correctly, how will it know that it was a sign anyway, so as to blank the display ?

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Wed 5 Dec 2018 23:13
Renault Megane - Incorrect dashboard speed limit display - focussed

It's just a French car programmed with the national characteristics - most of the population of France can't read speed limit signs either!

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Thu 6 Dec 2018 06:24
Renault Megane - Incorrect dashboard speed limit display - Happy Blue!

Irritating and stupid yes, but it is the driver's responsibility to ensure they don't break the speed limit. If you rely upon the car reading some cameras then it will make mistakes and you will exceed the limit at some point.

Use it as a guide but it's not the law.

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Thu 6 Dec 2018 06:34
Renault Megane - Incorrect dashboard speed limit display - badbusdriver

Our Honda Jazz uses a camera for speed limit recognition and it either displays the correct limit or nothing at all. I suspect the Megane must be using sat nav, and so is relying on clearly outdated info.

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Thu 6 Dec 2018 09:23
Renault Megane - Incorrect dashboard speed limit display - Andrew-T

Our Honda Jazz uses a camera for speed limit recognition and it either displays the correct limit or nothing at all.

BBD, tell me more about your Jazz. How does it react to a limit sign that has got too dirty to interpret correctly - I would suppose that it assumes no change, and continues to show the earlier limit? Does it recognise the small repeater signs?

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Thu 6 Dec 2018 09:45
Renault Megane - Incorrect dashboard speed limit display - badbusdriver

Our Honda Jazz uses a camera for speed limit recognition and it either displays the correct limit or nothing at all.

BBD, tell me more about your Jazz. How does it react to a limit sign that has got too dirty to interpret correctly - I would suppose that it assumes no change, and continues to show the earlier limit? Does it recognise the small repeater signs?

TBH Andrew, i'm not really sure what it does if the sign is too dirty to read. Presumably it either won't display anything, or continue to show whatever the last sign it read showed. From my own observation's, the signs in this neck of the woods (North East Scotland) are generally pretty clean, i can't think off the top of my head where i could try it!. I do seem to remember that when i lived in Lancashire and Cumbria the signs were very dirty, probably due to the traffic volume and the amount of trees nearby.

But the system does seem to be pretty accurate. For example, on the way out of the town i live in, there is a long section where it is 30mph, maybe 1.5 miles, then it raises to 40mph for about 200 meters, then into the national speed limit of 60mph. There is no delay in going from one section to the next, it shows on the dash as soon as you pass the sign.

Obviously for this type of camera based system to be accurate. It is dependant on the signs being readable, but also that the camera lense at the top of the windscreen is kept clean.

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