To trust or not to trust my GPS? That is the question.

[DrT]

Right, my TomTom One tells me that when the speedometer shows 80mph, GPS speed only 73mph or so. Is this normal? I would understand +-3 mph. So should we trust our GPS' when passing speed cameras?

Discuss.

[Makaveli]

Mine is incorrect too. 

Says I am going way faster than the GPS says, and I have noticed that those new stupid signs on the road that tell you your speed always say the same as the GPS not my speedometer.  Would probably take somewhere inbetween but when going past cameras I stick to less than what the speedometer says just to be sure 

[joesgti]

yea this is correct, most car spedos are out by about 10%, gps is the actual speed that you are going, god knows why they cant get it right with all the technology about these days but car manufactures probably have a good reason 

[Rhyso]

yea this is correct, most car spedos are out by about 10%, gps is the actual speed that you are going, god knows why they cant get it right with all the technology about these days but car manufactures probably have a good reason 

i think its so you dont get done for speeding!!

i guess from their point of view its safer to assume you are travelling faster than you actually are 

[Kiddfrost]

Yup, mines the same, TomTom says 92 when GTI says 100. I've been through loads of specs (50 limit) at 52 according to TomTom with cruise control on and havent been done yet.

[Peskarik]

80mph is not normal, it's against the law  Normal is above 100mph 

[Hurdy]

Yes again. My speedo reads accurately up to about thirty and then overreads the rest of the time. Going through average speed camera areas I always set the cruise to the GPS and watch everyone (apart from others who do the same) go backwards. I can set my cruise to 54mph with the GPS on a 50 stretch on the M1 and my speedo reads 60mph and yet the average speed camera's will only do you if you are 10%+1mph over. ie 56mph:nerd: as they also have to allow for 10% error readings on a speedo in the other direction.

[vanders]

TomTom & Road Angel agree on this one - my Angel shows about 10% speed differential too

[john_o]

use the GPS ! makes a huge difference as most folk are reading the speedo values....
And just to be sure remember to change lanes between cameras in a average speed zone 

or ..............


get a motorbike , and ignore the avg speed stuff