GPS Speed

[BigAndy]

Hi, I don't know if anyone remembers but I posted something about a big difference between my speedo and the speed readout of my GPS unit for my snooper. I've been in contact with snooper and it seems the GPS is more accurate meaning when my speedo sais i'm doing 80 i'm in fact only doing 73mph, and likewise 34 on my speedo is 30 in reality. Just thought you'd like to know, your cars aren't quite as quick as you think.

 

[Sy B]

Have you fitted alloy wheels to your car?

The difference in size in wheels alters the speed, I know there have been a few posts about this before on the forum, If you check out the fiatboo site (updates bottom of page) there is a speed calculator to work out how much roughly your speedo will be out.

SY B

 

[JohnP]

I have a RoadAngel GPS Detector and it's the same for me (standard wheels).

I let my boss use it in his Volvo S80 and he was disapointed to find that at 90 he was only doing 75. The speedo on the volvo was at least 10% out at all speeds!

 

[Anonymous]

Re: Re: GPS Speed

I'd rather it be lower than higher! Think your doing 75 and plod pulls you over for doing 90, i'd be well gutted!

 

[BigAndy]

Re: Re: Re: GPS Speed

I agree, better to read high than low, I was just supprised at how far out it was, but not as bad as the volvo sounds! I am running on 100% origernal HGT155 so wheels aren't adding to the offset.

 

[Dan]

Re: Re: Re: Re: GPS Speed

you'd expect the car's to leave the factory pretty much spot on, also...
i thought that the speedo was checked on the MOT, and that surely being 15mph out wouldn't be allowed??

 

[BigAndy]

Re: Re: Re: Re: Re: GPS Speed

Maybe they just check it's not reading low, how does this check work on Modded wheel cars? Could this be the way to keep modded cars off the road i've been looking for??!!

 

[patrick]

Re: Re: Re: Re: Re: Re: GPS Speed

Just looked all over this site, which is supposed to cover everything, and it doesnt actually mention the speedo

http://www.ukmot.com/manual/1-2.htm

 

[Alan]

Re: Re: Re: Re: Re: Re: Re: GPS Speed

i think they are only designed to be within 10% anyway