Zed Speedo V's GPS

[MickJ]

Anyone finding the same, speedo is reading at least 5mph more than GPS readout? and this was using two GPS units which both gave identical readings..... I know you only use the rev counter

[Guest prescience]

Usual order is:

GPS

Digital = GPS + 2-3mph

Analogue = GPS + 5-6mph

[Kuro]

Usual order is:

GPS

Digital = GPS + 2-3mph

Analogue = GPS + 5-6mph

 

Ditto

 

There's a not a great deal in it (at any speed) when using the digital unit. I actually thought there'd be a lot more...

[Chris`I]

All speedo's I've ever measured read about 5MPH more @ 60-70MPH over a GPS. I beleive this is manufacturers covering their behinds so that when we sit at 70MPH on the motorway or whatever we dont get done for speeding. They need to build in a little contigency as I dont beleive their are completely accurate.

 

I beleive I once read the digi readout is taken from somewhere different to the analogue dial and this explains the difference there. But that is compete hersay

[Trev-the-Rev]

I read somewhere that manufacturers are permitted up to a 10% margin of accuracy in their speedometers. I guess this is why you will usually not get pulled for doing 77mph on a motorway for example.

[Chris`I]

A few years back my friends dad was an advanced police driving instructor. Back then the guidlines given to traffic police was speed limit +10% + 3MPH. So for motorways you got 80MPH before they'd ticket ya. He also said that you could easliy do 85MPH without being done as long as you arent all over the place or tailgating. Not that I condone speeding of course

[MickJ]

A few years back my friends dad was an advanced police driving instructor. Back then the guidlines given to traffic police was speed limit +10% + 3MPH. So for motorways you got 80MPH before they'd ticket ya. He also said that you could easliy do 85MPH without being done as long as you arent all over the place or tailgating. Not that I condone speeding of course

 

Motorway cop mate told me it was speed limit + 10% + 2mph, but what's 1mph between friends.

[Dan]

I've heard the Speed Limit + 10% + 3mph before. So that gives us 80 mph before we get booked.

If we than add 10% for speedometer error, we can do 88 mph without a care in the world

 

So then why did I get done at 86 mph three weeks ago

 

P.S. Yes, I'm being silly.

 

By the way, the most innacurate speedometer ever measured by What Car ? magazine was a 1983 Rolls Royce Silver Spirit which was 11% fast at 70mph !

I have no idea why I remember this stuff !!!

[Billy7766]

A few years back my friends dad was an advanced police driving instructor. Back then the guidlines given to traffic police was speed limit +10% + 3MPH. So for motorways you got 80MPH before they'd ticket ya. He also said that you could easliy do 85MPH without being done as long as you arent all over the place or tailgating. Not that I condone speeding of course

 

I got nailed doing 87mph on an empty motorway last jan (hence the natty picture on the left here; got to use the photo for something!) I'd suggest being very careful at or over 85

[Stew]

My digi speedo is 3 mph out at 70 odd. I usually set cruise control for about 77 and this is 74 on my gps readout. The analogue (oe anal speedo) reads about 90 or something just as inconsistant!

[Jimbo]

My digi speedo is 3 mph out at 70 odd. I usually set cruise control for about 77 and this is 74 on my gps readout. The analogue (oe anal speedo) reads about 90 or something just as inconsistant!

 

I use the road angel navigator and at 70MPH on the clock GPS Shows 65MPH I havent compared to digi speedow yet though.

[Chris`I]

A few years back my friends dad was an advanced police driving instructor. Back then the guidlines given to traffic police was speed limit +10% + 3MPH. So for motorways you got 80MPH before they'd ticket ya. He also said that you could easliy do 85MPH without being done as long as you arent all over the place or tailgating. Not that I condone speeding of course

 

I got nailed doing 87mph on an empty motorway last jan (hence the natty picture on the left here; got to use the photo for something!) I'd suggest being very careful at or over 85

 

Ouch mate, sorry to hear that. I have a friend who got nailed for doing 56MPH in a 50 zone. It is down to the copper in question, as you say you have to be careful, as they can actually do you for doing 71MPH in a 70 if they are having a bad day