e90 speedometer readings

[karl hafner]

While all BMW's appear to have their speedometers reading 1-3 miles faster than
the correct ground speed the E90 is worse. I just took my 2006 e90 and put
my wife's GPS in it and at 64mph it is going 60. To get a correct ground speed
of 75 you have to go 79mph (we set the cruise for stability of speed). Is this
amount of error common in the e90's and is there anything you can do to correct it? It is a 330i. I also have a 525i and a 528i and they are off by 2 to 3 mph at the same speeds. thanks karl hafner

[drz]

The 'error' is not really error. This is very intentional. Auto makers in Germany can get in really big trouble if the speedometer is slow, so BMW makes theirs a little fast. Since your 330i has a higher power/weight ration than your 5ers, perhaps BMW used a larger margin -- again, to ensure compliance with traffic laws.

How realible is the speed reading from the GPS? I would look for something like a radar gun or a velocimeter from a physics lab instead.

I doubt you have anything about which to worry. Hopefully other E90 owners are able to confirm my hunch.

[Phatrician]

Yeah, my 2001 330i is about 5 miles over. My previous '99 328i was about 5 as well.
Also, what is "ground speed"? Does your Bimmer get airborne at some point? Are you not ALWAYS on the ground?
Also, my wife doesn't have a gps, nor do I have a wife, but I do get pulled over from time to time, so that's how I know.

thanks karl hafner