Normally i dont even look at my Speedo as it is hard to read anything past 60 MPH the way my seat is adjusted. I happen to glance at my scanguage MPH today on the highway and my speedo , very odd that the speedo was about 6 to 8 MPH slower then the scanguage. I think the Scanguage is reading correct, and the speedo is off, has anyone had this issue?

 

Yes that has been a known problem since the beginning. I will admit mine is only 2mph off.

 

The speedo usually reads high. Did you changes wheels or tires? If the sizes of your wheels or tires changed, then it could make that much of a difference.

Richh

 

Mine also reads ~2mph shy at 60 vs scangauge - Your 7-8 mph, what speed is that at? (careful - no racing! )

 

Pretty slow actually, under 40. No tire swap in over 2 months, I did just do 2 seafoam treatments,
Will watch it more closer tonight when I go to work

 

Is your SGII adjusted based on a GPS? If not do that first as the SGII needs it most of the time.

In my MINI the Speedo is almost spot on because I change to 215/45-17 tires. The surprise for me is that my Odo reads about 3% low.
I guess I am ok with showing fewer miles than I actually use.

In my Miata both the Speedo and Odo are spot on with GPS confirmation.

 

What you're seeing is normal for MINIs. Typically, in a MINI with stock tires, the speedometer will read a few percent fast and the odometer will be very close to correct.

When you switched to larger-diameter tires, your car is now traveling further per wheel revolution than before, so your speedometer is closer to correct. But now your odometer will read low, as you've already noticed.

 

Mine has always read 2 mph's higher according to my Scangauge and Nuvi. Typical 205/45/R17 tires on mine.

 

Same here.

 

Whatever problem I was having is gone, I have watched it the past 2 nights and it is almost spot on, from 10 MPH all the way to 70, read perfect. Just another quirk

 

I am confused. Would not changing tires also throw off the scanguage too?

 

I was just referring to thulchatt's post, telling him that it's normal for the speedometer and odometer to read lower after switching to larger tires.

But you're correct - switching to larger (or smaller) tires will affect a Scangauge as well.