Speedo accuracy- sat nav [Archive] - VW T4 Forum - VW T5 Forum

Speedo accuracy- sat nav

11-04-09, 08:15
I was wondering how accurate the speedo was on the T4.

Does the sat nav show accurate speed. If so what is your showing.

I'm waiting to get an I phone with google maps sat nav. Anyone used one?

I've been thinking of 235 50 18s instead of 225 40 18. I know my bike speedos have always over read!

Thanks Paul

team french
11-04-09, 09:00
theres a diffrence of 5mph at 70 between clocks and satnav(speedo fast) on my van. But i was thinking the other day, will the satnav give an accurate speed/distance if your doing alot of hills? ie is it able to calculate/compensate for altitude as well as latitude and longditude?

11-04-09, 10:13
Sat nav is only accurate along a flat surface. But still more accurate than most speedos. T:

11-04-09, 10:16
with my 275/35/20's my speedo is same as sat/navT:

team french
11-04-09, 10:17
Sat nav is only accurate along a flat surface. But still more accurate than most speedos. T:

thought the world was round not flatI:I:

i was thinking that would be the caseT:

11-04-09, 17:29
thought the world was round not flatI:I:

Don't you ever come to Cornwall spreading that kind of talk!! Whatever next :eek: :D

11-04-09, 17:37
I certainly wouldn't rely on the iPhone satnav for turn by turn directions, it's a good feature for a phone, but is no substitute for a Tomtom/navman etc.

Runs the battery down in no time too.

12-04-09, 07:03
I am waiting for the new version 3 iphone software, which will allow proper map based navigation software to run, THEN I will get an iphone. (they will prob release a new version of the phone soon as well)

TomTom and Copilot have both shown working versions of their satnavs on the iphone at shows, but were not able to release them because of firmware issues and a clause in the developers kit, forbidding "turn by turn map based navigation software"

I have copilot and tomtom on my windows phone (XDA Orbit2) and I reckon Copilot is nicer to use.

Back to Satnav...with my old 245 45 18's my sat nav and speedo were identical, on 240 40 18 my speedo overreads about 4% (The 245/45/18's increased the rolling radius the new ones are closer to the original )