So I took my car on a business trip today.

Noticed something strange, in my last car my Garmin matched up with the speedometer in my old car.

My speedometer in my G35 is about 8kms higher than my Garmin indicates.

120km/h on the speedometer and 112km/h on the Garmin GPS?

Going to work at the same time as my wife tomorrow and will try and pace our speed and see what's up.

Any one have any speedometer issues?

Was hard to get a sense of exactly how fast I was going as the car is very smooth on the highway.

 

Are you still on stock wheel sizes?

 

^+1 and Search is your friend!

Incorrect speedo

Incorrect Speedo 2

Enjoy!

 

If 18's are stock with the G35S 6MT then yes.

 

My 07 G35X was between 6-9km/hr too high, at highway speeds (new factory wheels/tires). The faster I went the greater the error. I found it annoying but lived with it for almost four years until last night. I asked the dealer about it shortly after I bought it in 07 and they told me there was nothing they could do and that the govnt allows a certain amount of error.
My 11 G37S 6MT is bang on.

 

Yamaha has this on their R series motorcycles (R6 and R1) to make you think you are going faster than you really are so that you will not drive as fast

 

i get the same thing in my '07. actually like it, keeps me from speeding

 

My 08' is spot on

 

Never really checked mine, ehhh I don't speed anyway hahaha, and if I do it's on my 07 Yamaha FZ1.

 

mine is 1-2mph max off compared to those GPS and road speed check signs... id say its spot on since those road check machines are purposely set to show 1-2mph higher in most areas to keep you going slower.

 

I've been reading some about this topic, and it seems neither can be considered accurate. There are many factors and variables involved that can put one over the other (i.e. gps vs. speedo). Generally, it seems GPS receivers with WAAS is more accurate than a speedometer at higher speeds, but speedometers bode well for lower speeds and/or changes in altitude or road conditions, or even in cases where the GPS unit cannot reliably lock-down a signal.

 

Followed my wife on the highway tonight in a short experiment.

We were in communication on our cell phones.

She set her cruise control at 100km/h, I had to go 108km/h to keep pace with her.

She set it at 110 km/h, My speedometer was just under 120km/h to keep pace.

 

Thats a big difference, but that could also be because the other car is a bit off as well causing such a big difference imo

 

Many speedometers are inaccurate, and they almost always read high. Car and Driver ran an article about it many years ago:
http://www.caranddriver.com/features...andal!-feature

I haven't had a chance to test my '08 G35 yet, but my '02 Altima reads about 4 mph high when travelling at 70 mph.

 

Like I wrote earlier, my 07 G35X speedo was always off by the same amount.
I also tested/compared it to multiple other vehicles and a few GPS devices. I used the same Garmin (and a GPS Phone) in the G and then in a few other vehicles. The Garmin always matched the speedo in other vehicles (within 1km/h) but was always 8-9km/h off in the G, at highway speeds.

The other test I performed was within the G itself. I set cruise at 100km/h on the speedo, reset the AvgSpeed on the LCD between the Tach and Speedo. After about 30 seconds the LCD shows you your actual avg speed. It would show 92km/h when the cruise was set to 100 on the speedo. The LCD was the same reading as the GPS devices.

Unfortunately, there's not much you can do about it.

If you've never had this problem, be glad, you don't realize how annoying it really is.