Speedometer calibration ?

[Thekuai]

When my speedo reads 63 mph I am going 60mph. If I'm reading these posts correctly, I have to change it to -2.5%?

[rogersleaf]

When my speedo reads 63 mph I am going 60mph. If I'm reading these posts correctly, I have to change it to -2.5%?

No, will be off by 5%.

[Thekuai]

When my speedo reads 63 mph I am going 60mph. If I'm reading these posts correctly, I have to change it to -2.5%?

No, will be off by 5%.

I meant on the special calibration page where the max adjustment is + or - 2.5%

[rogersleaf]

When my speedo reads 63 mph I am going 60mph. If I'm reading these posts correctly, I have to change it to -2.5%?

No, will be off by 5%.

I meant on the special calibration page where the max adjustment is + or - 2.5%

My experience with that adjustment screen is it did absolutely nothing. Speedo & odometer we’re off the same 5% after changing the settings.

[powersurge]

As I always say with instruments... People should stop expecting all dials and meters to show exact numbers!!!!

Even If You are using a voltage meter, or digital thermometer, there will be some variability..

2.5% or even 5% of speed difference is nothing.. Worry about more important things... And I say this with love in my heart.....

[rogersleaf]

2.5% or even 5% of speed difference is nothing.. Worry about more important things... And I say this with love in my heart.....

In most cases I would agree. However, this was a leased vehicle that I was being charged based off of the inaccurate odometer calibration (which was set to NMAC’s favor by 5%). I’m no lawyer, but think this is called fraud.

[GerryAZ]

The menu adjustment +/- 2.5% was enough to calibrate my 2011 to within 1 mi/hr. I tried to use the menu adjustment on my 2015 when I first purchased it, but the car automatically returned the setting to zero after driving a while. I eventually found that the speedometer was within 1 mi/hr of a fast-response GPS with the original tires inflated to 44 psi. I noticed no change with the first set of replacement tires. I recently purchased new tires one size larger so I planned to use the menu adjustment to compensate. Again, the menu adjustment returned to zero after driving. I then discovered that the speedometer was still within 1 mi/hr (fast-response GPS generally indicated 1 mi/hr higher than speedometer). I eventually concluded that the navigation system GPS must send a calibration signal to the speedometer periodically (it also sends the clock signal to the eyebrow display so the clock never needs to be set). It does not calibrate the odometer so it now reads about 3.5% lower than actual distance diriven.

Edited to add: I don't know when the change was made, but the clock in the 2011 required periodic resetting and the +/- 2.5% adjustment in the menu was effective. The 2015 seems to set the clock and calibrate the speedometer automatically from the navigation system GPS.

[GerryAZ]

The menu adjustment +/- 2.5% was enough to calibrate my 2011 to within 1 mi/hr. I tried to use the menu adjustment on my 2015 when I first purchased it, but the car automatically returned the setting to zero after driving a while. I eventually found that the speedometer was within 1 mi/hr of a fast-response GPS with the original tires inflated to 44 psi. I noticed no change with the first set of replacement tires. I recently purchased new tires one size larger so I planned to use the menu adjustment to compensate. Again, the menu adjustment returned to zero after driving. I then discovered that the speedometer was still within 1 mi/hr (fast-response GPS generally indicated 1 mi/hr higher than speedometer). I eventually concluded that the navigation system GPS must send a calibration signal to the speedometer periodically (it also sends the clock signal to the eyebrow display so the clock never needs to be set). It does not calibrate the odometer so it now reads about 3.5% lower than actual distance diriven.

Edited to add: I don't know when the change was made, but the clock in the 2011 required periodic resetting and the +/- 2.5% adjustment in the menu was effective. The 2015 seems to set the clock and calibrate the speedometer automatically from the navigation system GPS.

I have driven the 2019 enough to confirm its speedometer (both analog and digital displays) is also accurate vs. my GPS regardless of tire pressures in the range of 36 to 44 psi. Therefore, it appears the GPS in the navigation system is providing signals to set the clock and calibrate the speedometer like the 2015 did. The odometer registers between 2% and 3% fewer miles than actually driven with OEM tires inflated to 44 psi so I will get a few extra miles of warranty coverage.