If I’m on the motorway, and I adhere to the speed limit, I get overtaken continuously by lorries. I’ve noticed it especially if going trough roadworks, where the speed limit tends to be 40 or so. What gives?
Its 50 in nearly all roadworks and almost always averaged out.
Drive faster your car may read 40mph but you might only be doing 36 or 37 mph.
You’re under the limit. If the limit is 40 you’re probably doing 39/40 as indicated on your speedo? Really you’re most likely doing 36 as car speedos aren’t particularly accurate. Just continue as you’re doing but don’t do it in the middle lane 
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harrawaffa:
You’re under the limit. If the limit is 40 you’re probably doing 39/40 as indicated on your speedo? Really you’re most likely doing 36 as car speedos aren’t particularly accurate. Just continue as you’re doing but don’t do it in the middle lane
As above - car speedos are not calibrated and will always show more than actually doing
The speed readout from a satnav is lot more accurate
Most cars tootle thro the roadworks like they have all day,too busy talking to passengers or just don’t realise they may actually be other road users about bloody annoying tbh,if its a Tuesday normally me flying past as its my Friday and normally “driving hours bingo” to get back lol.
Congratulations on sticking to the speed limit.
Chufty badge en route to you asap.
Speed limit?.. Thought speed signs were how long it took to get thro on the limiter ?.. Lol 
Most speed limits through road works are AVRAGE understand why that means it helps also have you speedo calibrated that might die a more accurate speed easy really
If the speed limit sign says 50mph then the speed limit is 50mph not an average of 50mph, although the speed cameras calculate the average speed over a given distance you can still get done for exceeding a 50mph speed limit.
As has been said most speedometers show a lower speed than you are actually travelling at … and some lorry drivers just like to exceed the speed limit
Daytrunker:
,if its a Tuesday normally me flying past as its my Friday and normally “driving hours bingo” to get back lol.
I don’t know why this made me laugh. It did lol
As mentioned your car speedo will be slightly out
I usually go off the sat nav speed and always seem to catch people in average zones so i’m guessing they are doing the same
truck drivers wouldn’t set the cruise control to 51/52 on a 50 would they?
Recently did a months work for a Travis Perkins affiliated company and all their vehicles are tracked. Got reported for nine speed infringements in first two weeks where truck speedo said 30 and I was actually doing 32-33mph. Who’s right and who’s wrong. Was glad to end my assignment there as it was driving me bonkers.
Krash:
As mentioned your car speedo will be slightly out
I usually go off the sat nav speed and always seem to catch people in average zones so i’m guessing they are doing the same
Most sat navs read 2 mph slower than actual speed. something to do with a cheap( slow) gps receiver in most sat navs.
itsa_me:
Krash:
As mentioned your car speedo will be slightly out
I usually go off the sat nav speed and always seem to catch people in average zones so i’m guessing they are doing the sameMost sat navs read 2 mph slower than actual speed. something to do with a cheap( slow) gps receiver in most sat navs.
I wonder how that would work? If slow to register at point A would the same unit not also be slow to register at point B? As I understand it the TomTom (presumably others too) units measure speed from the distance between different positions and the time taken to move between them. So if a unit is slow to register wouldn`t it be equally slow at all points?
Franglais:
itsa_me:
Krash:
As mentioned your car speedo will be slightly out
I usually go off the sat nav speed and always seem to catch people in average zones so i’m guessing they are doing the sameMost sat navs read 2 mph slower than actual speed. something to do with a cheap( slow) gps receiver in most sat navs.
I wonder how that would work? If slow to register at point A would the same unit not also be slow to register at point B? As I understand it the TomTom (presumably others too) units measure speed from the distance between different positions and the time taken to move between them. So if a unit is slow to register wouldn`t it be equally slow at all points?
I think its got something to do how accurate they are. Consumer level GPS isn’t that accurate to begin with.
Radar19:
Franglais:
itsa_me:
Krash:
As mentioned your car speedo will be slightly out
I usually go off the sat nav speed and always seem to catch people in average zones so i’m guessing they are doing the sameMost sat navs read 2 mph slower than actual speed. something to do with a cheap( slow) gps receiver in most sat navs.
I wonder how that would work? If slow to register at point A would the same unit not also be slow to register at point B? As I understand it the TomTom (presumably others too) units measure speed from the distance between different positions and the time taken to move between them. So if a unit is slow to register wouldn`t it be equally slow at all points?
I think its got something to do how accurate they are. Consumer level GPS isn’t that accurate to begin with.
Consumer GPS may not be as accurate as military GPS but I`d question “GPS isn’t that accurate to begin with.”
Re-reading “itsa-me” s comment maybe he/she is confusing latency with speed? Some sat-navs will have a delay in displaying current speed, so when accelerating the speed shown will lag behind true speed and be slower. Not really relevant in our scenario of cruising through roadworks. Slowness to display data is not the same as slow speed.
Franglais:
itsa_me:
Krash:
As mentioned your car speedo will be slightly out
I usually go off the sat nav speed and always seem to catch people in average zones so i’m guessing they are doing the sameMost sat navs read 2 mph slower than actual speed. something to do with a cheap( slow) gps receiver in most sat navs.
I wonder how that would work? If slow to register at point A would the same unit not also be slow to register at point B? As I understand it the TomTom (presumably others too) units measure speed from the distance between different positions and the time taken to move between them. So if a unit is slow to register wouldn`t it be equally slow at all points?
I also agree with you on that…
Drive it like you stole it 