Simple and probably stupid question about percentage on speedo

[drgtr]

If car speedo reads 50kmh and GPS reads 58kmh

https://percentagecalculator.net/

do I type in from that calculator as the following

What is the percentage increase/decrease
from
50 to 58? Or is it the other way around?

from 50 to 58 returns 16%




Reason asking because the Tripometer shows 12.5km distance travelled while GPS distance travelled which is 14.91km travelled.
Which is 19.28% difference.


Trying to get what is right and wrong so eventually I can work out my fuel consumption lol

[the evil twin]

Technically, you should always work out % of an error against an actual parameter.
IE actual = 100% and error (or difference) is a percentage of actual

Your Speedo at 58 KPH actual speed is under reading by 8 KPH or 14%
Your Odo at 14.91 actual travelled is under reading by 2.4 K's or 16%

This would mean if you adjust the speedo drive cog in the gearbox so the Odo was accurate the speedo would overread which, indeed, it should as required by ADR.

[drgtr]

Ill definately get a cog to fix things up but at this point.

Which percentage am I going by then to work out fuel consumption? The 14 percent or 16 percent difference?

Thanks Mate

[the evil twin]

Oops my bad...

Sorry to be confusing but I didn't know that is what you wanted to work out.
When you are working out an actual unknown from an erroneous known parameter the figure is as you posted.

Sooo... when the Odo reads 12.5 (known but wrong) and you want to know actual it will be 12.5 X 1.19
IE for every 1 Klm shown as travelled you will have gone 19% ish further than that.

For that calc link
using 14.9 as value 1 and 12.5 as value 2 returns 16% or the amount of error in %
using 12.5 as value 1 and 14.9 as value 2 returns 19% or the amount of compensation needed in %

You need to apply the 2nd number IE 19%

[drgtr]

Oops my bad...

Sorry to be confusing but I didn't know that is what you wanted to work out.
When you are working out an actual unknown from an erroneous known parameter the figure is as you posted.

Sooo... when the Odo reads 12.5 (known but wrong) and you want to know actual it will be 12.5 X 1.19
IE for every 1 Klm shown as travelled you will have gone 19% ish further than that

lol. Thankyou . Its my fault. I probably dont articulate well.

So basically add on 19 percent on top or whatever is showing on the Tripometer everytime I fill up?


Say I done 460kms

so 1.19 x 460kms = real distance travelled?



To correct I seen people buy those cogs. They work out how many teeth their car has and they swap over

74782

[GQtdauto]

If it means that much and it's a GQ there is a fix for your speedo on here somewhere just search for it , mines 10 kilometres out when tyres are new when worn a bit about 6 kilometres an hour but as long as actual speed is at the speed limit it means nothing really .

[the evil twin]

So basically add on 19 percent on top or whatever is showing on the Tripometer everytime I fill up?


Say I done 460kms

so 1.19 x 460kms = real distance travelled?


Yep... I'd use 20% just to make it easy

[drgtr]

Yep... I'd use 20% just to make it easy


Legend. Cheers Mate. Appreciate your help always

[drgtr]

If it means that much and it's a GQ there is a fix for your speedo on here somewhere just search for it , mines 10 kilometres out when tyres are new when worn a bit about 6 kilometres an hour but as long as actual speed is at the speed limit it means nothing really .

Its a GU.
lol Honestly just want to work out fuel consumption. Thats it.
Im happy driving my 42tdi.
I love it.

When I drove the prado. It felt like a soccers mums car.

This patrol I feel like a man! haha