Discussion
I don't know if the ML has the same software as the R171 but TMC was added last year which gives you dynamic display of traffic jams etc. In theory anyway, in practice the information is often not up to date. It's probably driven by the same data that causes motorway signage to be completely inaccurate half the time. Incidentally you might find a copy on eBay from time to time. I bought my upgrade half price and it was a brand new genuine sealed copy.
This version jumped from 4 to 6.1 around 6 mths ago so you probably just missed out. EBay often has 6.1 on there (watch for people selling the files, not the actual disks!).
No-one seems to be able to explain the difference between 6.1 and 6.2 but it would not appear to be significant.
I've seen comments suggesting that older disks have a lag such that the instructions are a bit late - I really notice that on roundabouts, where it says 'turn left now', about 20yds too late. V6.x apparently fixes this, so it may be worth casually mentioning this to your dealer and they *might* upgrade the disk anyway. Does yours sometimes also give you the wrong exit number off roundabouts? If so, mention that too.
The TMC data is provided by ITIS. I don't know if they rely on it totally, but one of its inputs is Floating Vehicle Data (FVD) using data supplied by AA patrols, National Express Coaches and Eddie Stobart trucks. So presumeably its accuract depends upon on how many of those vehicles are also caught up in the jam you're heading for.
No-one seems to be able to explain the difference between 6.1 and 6.2 but it would not appear to be significant.
I've seen comments suggesting that older disks have a lag such that the instructions are a bit late - I really notice that on roundabouts, where it says 'turn left now', about 20yds too late. V6.x apparently fixes this, so it may be worth casually mentioning this to your dealer and they *might* upgrade the disk anyway. Does yours sometimes also give you the wrong exit number off roundabouts? If so, mention that too.
The TMC data is provided by ITIS. I don't know if they rely on it totally, but one of its inputs is Floating Vehicle Data (FVD) using data supplied by AA patrols, National Express Coaches and Eddie Stobart trucks. So presumeably its accuract depends upon on how many of those vehicles are also caught up in the jam you're heading for.
A couple of Saturdays ago TMC showed slow moving traffic a couple of miles either side of junction 18 of the M4. At the time, there was no traffic to speak of. On Sunday evening when we came through there again, all the overlaid symbols were in exactly the same places on the map, but there was still no traffic. You could only conclude the local collection system had broken down and it was showing data from Friday or earlier.
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