[norbtx]

So I’ve been using Waze and I’ve noticed that the M5’s speedo reads 2-3 mph faster than what the gps based Waze shows. For example when the speedo reads 70mph, Waze says actual speed is 68-67. Is that normal or within spec?

[Vic55]

I seeing about a 5% variance.

I recently got rolled at 123 (in cabin) and he had 117. After a nice convo he let me go but I have been checking my speedo vs local posted mph devices and its always around 5%.

[dardeca]

Originally Posted by Vic55

I seeing about a 5% variance.

I recently got rolled at 123 (in cabin) and he had 117. After a nice convo he let me go but I have been checking my speedo vs local posted mph devices and its always around 5%.

No ticket doing 117? You must be one hell of a talker!

[MysticBlue]

Yes, this is totally normal. Most cars read a little over. European cars especially are known to run about 3 or 4 % over, on average, sometimes as little as 1 or 2%, sometimes as much as 5%. Various regulations around the world, but they basically come down to the fact that speedo can't read under real speed, but it can read over. Since there can be a 3 or 4% variance when looking at a large number of cars, they just make it read on the high side to make sure all there cars will be in compliance. This has been the case for many years. And generally speaking, velocity measure using GPS is very accurate.

[norbtx]

I understand why it would read over, but these things are digital now. Can't they have the on board gps help with accuracy? The car sets the time, and time zone based on gps and its accurate. Love that cars are tuned to the atomic clock now. I just want that level of accuracy since the speedo is non mechanical.

[lemetier]

Originally Posted by norbtx

I understand why it would read over, but these things are digital now. Can't they have the on board gps help with accuracy? The car sets the time, and time zone based on gps and its accurate. Love that cars are tuned to the atomic clock now. I just want that level of accuracy since the speedo is non mechanical.

The speedo isn't as inaccurate as you think and GPS derived speed is actually more inaccurate for land vehicle speed due to deviations in elevation when used for real time comparison unless 5 or more satellite signals are acquired. Even then, there is still a delay while the 3D triangulated velocity is calculated. IIRC, WAZE is 2D speed most of the time.

[Ex_Stig]

BMWs tolerance allows for the speedo to read fast by up to 10% +2.5mph.

I've got it documented somewhere, as this has been questioned a lot over the years, but at the moment I am too lazy to find it.

[lemetier]

Originally Posted by GNALUZU

BMWs tolerance allows for the speedo to read fast by up to 10% +2.5mph.

I've got it documented somewhere, as this has been questioned a lot over the years, but at the moment I am too lazy to find it.

It was in the days of mechanical speedometers. Same UN GTR applies with the digital speedometer (speed displayed may never be less than actual, but up to 10% higher + 4km/h for passenger cars). Every F90 I've driven has been within 0.99% with most at the 0.6% target.

[swisstype]

I have the Radenso Detector with GPS on, and leave it to show MPH while I am driving. I see it get more disparate the faster I go, which makes sense. I see 2-4 MPH depending on Speed.

[Aaaaaaaaa]

Originally Posted by dardeca

No ticket doing 117? You must be one hell of a talker!

Must be the 11-99 Foundation Supporter license plate frame.

[devondragon]

My F13 M6 read about 8-9% high, my F90 M5 reads about 2% high.