I have a handheld SIRF III gps receiver. At freeway speeds, my speedometer is spot on. Journey 5AT with the sport wheel pkg.

 

Question - Did anyone with this problem ever get it resolved.
My speedo is out by about the same amount as yours Arctic and the margin of error increases with velocity.
(km/h)
66=60
88=80
109=100
132=120
140=136
This is annoying. It's a guessing game as to how fast I am actually driving.

I used two methods to confirm the speedo is inaccurate:

1. Portable GPS - I also tested the same GPS in 3 other vehicles and found it to be the same as there speedos at all speeds.
2. The G35's own DOT MATRIX LIQUID CRYSTAL DISPLAY (DMLCD), located between the speedo and tach.
While on a long stretch of level road (hwy 401) I set the cruise at 110km/h (on the speedo) and I reset the DMLCD while in the L/100km & km/h mode. The DMLCD displays the avg speed (which does not vary) as 101km/h.

The amount of speedo error is the same when tested in both methods.

 

I have just learned to live with the error on my speedo.

 

did you ask Guelph Infiniti about it?

 

Either that, or they like the fact that your warranty will expire faster than it should.

 

No I never bothered.
The funny thing was that I checked both speedo and the odometer with my portable GPS. The speedo was out yet my odometer was accurate.

 

OK iv checked mine as well and mine is on average 3-5 mph not more than that on multiple tests so im ko with it.