speed check box on side of road

[BUSHWHACKER]

All speedo's in all cars are inacurate. that said they are accurate at 30 mph on test m/c when car is designed. the difference / inaccuracy occurs due to tyre tread wear / tyre make / road conditions / wear in gearbox etc etc - which is why coppers allow a 10% margin before they'll nick you.
I once got pulled at 4 in the morning - dry road - no other traffic doing 33.4mph in a 30 zone !!!
when my speedo reads 70 - my sat nav says 63mph. wether that'll stand up in court is a different matter!!

The speedo in our Celica reads 76mph, the sat nav says 70mph!

Will I need to get my sat-nav re-calibrated, or take Toyota to court 'cos their cars don't do the speed thats indicated?

[Tallyman]

Tested my sat-nav on the Surf and the wife's Corsa. Surf 30mph is 30 on the sat-nav. 70mph on the sat-nav is 77 in the Surf.

On the wife's Corsa the speedo and the sat-nav agree all the way to 70mph, so speedo's can be accurate.

As regards the roadside speed warnings, some of these appear to be set low to slow traffic. On the way to our gun club there is one such that I have approached at an indicated 28mph and it's flashing to tell me I'm going too fast, whereas I know I'm under the limit, so Pirate-Storm may well have come across one that is similarly set too low.

[That Ruddy Squirrel]

There's one of them fancy signs down here by Ardingly college, the road has a 40mph limit, I was doing roughly 30 (having a lazy mooch) and it told me to slow down

[Apache]

Sat nav speed is very accurate but only if you drive in a straight line. Checking speed while cornering will throw it.

The signs are not set accurately so I wouldn't worry too much

[PDR]

Mine is the opposite in that it reads LOW…

When I am doing an indicated 30 mph on the speedo the GPS reads 35/36 mph.

When I set my Cruise Control to its upper limit of 65 mph, I am really cruising at 70mph.

I have to make sure that I keep to a indicated (speedo) reading of 25mph while passing speed cameras in a 30 mph zone just to be safe.

[AuldNick]

Aint it EU law that all speedo's read at least 12% over on new cars / bikes IE it lies for safteys sake?

[fatfires]

best way ive found for spedo check..drive alongside a new renault - they have got big digi speedos, easily seen when alongside

[AuldNick]

"drive alongside a new renault"

Aint they always in the garage gettin sorted brokedown or recall french car stylo?