I have a Garmin GPS and when it shows 100km/h on my GPS, my 2009 outlander's speedometer is showing 104 km/h. is there a way to correct the situation ?

How precise is a GPS when it comes to speed anyway ?

Thanx

 

I would trust your Outlander over your Garmin. Your Garmin calculates speed by triangulating your latitude/ longitude, and then measuring the change in that latitude/ longitude over a set time. (Usually a second or 2). Your Garmin is only accurate down to 1-3 meters, if it uses WAAS.

 

I'll try checking my speed with my friends GPS to see if't the same as mine. When I had my pathfinder the speed of it and my GPs was right on.

 

When I have passed through restrictions of speed limit with boards electronics, they exactly give me the same speed that speedometer on my Out. . .

 

Honestly, I'd trust the GPS.

Your profile says you have an '09, so I doubt your tires are bald. Maybe go back to the dealership and talk to them, if they give you flack, ask to take out another Outlander and compare the GPS to that Outlander.

 

Chances are your garmin is correct. An allowable degree of error on a speedo is 4% before calibration is required(at least where I live). At low speeds the GPS speed is more difficult to calculate and you can expect greater errors. At a 1 second sample rate and at 100kms/hr with a large number of averaged samples, the garmin is going to produce a very accurate result.

As your tires wear, their circumference will decrease and you will get closer to an accurate reading. Tire pressure makes a difference as well. Tires made by different manufacturers will have slight variances in circumference as well. You are within all limits.

 

GPS is more accurate

 

What I'm gonna do is also compare the odometer to the distance on the GPS next time I go on a longer trip. I don't care that much about the speed acuracy then the distance. cuz if the odometer is wrong then my warranty could be shorten quite a bit.

 

the speedo is normally calibrated for tires that are 1 to 2 sizes bigger than factory fitted ones.

in the case of the outlander, you will find that if you upsize your tires, your speedo will read alright. i've used 235/55R18 vs 225/55R18, and the speedo reads within 1km/h of actual speed.

 

In my experience, every day I travel in helicopter and I have the opportunity to see the cockpit's instrumentation, so I can say that exist difference between the readouts for altitude, course and speed between aircraft's intruments and GPS devices, reason why I prefer Outie's speedometer over GPS; in addition, I have verified speedometer vs systems speed detection (police), and the readout speeds are identical. . .