Is speedometer calibration possible?

[evolver]

Speedometer in my E70 consistently shows higher readouts that the real speed. It shows 55 when I'm doing 51-52 according to a stationary police speed warning sign or my GPS. I tend to believe the GPS and the speed gun. The other day I was at the dealership for service and asked them about recalibration. I was told that there is no recalibration possible.

Is this true or does it sound more like the SA did not want to bother taking such work order?


Thank you!

[newtoav]

Not sure about recalibration, but FWIW, my E90 consistently indicated 10% over the real speed, my E70 seems to be more like 8% (sounds similar to yours). I can't believe that this is not a deliberate move by BMW. My thoughts are that they:

- Err on the side of caution, by indicating more than actual, people tend to drive more slowly
- Like the fact that their cars seem faster than they really are
- Just don't care

Anyway, you can always just subtract 8% in your head... keeps the mind sharp!

[Denalio]

This is quite normal all manufactures do it. They calibrate 3-9 km/hr under absolute accurate.

[spyderdoc]

As I've mentioned before on a previous similar thread, I wonder if the odometer is also 8-10% off. I don't have a GPS to accurately (well, as accurately as a GPS can measure) compare readings. In CA, they don't really have nice readable mile markers like they do in most other states, like AZ. If in fact the odometer is off as well, that means our warranties will expire 8-10% prematurely, and when it comes time to sell the car, it will read out higher than actual miles, decreasing value of car.....Those that lease will be paying 10% more for their miles.....So on and so forth......

[JCL]

The BMW spec is 2.4 mph + 10% as a maximum error IIRC. Regulations require that there be no under-reading, and there is a natural range of accuracy due to manufacturing tolerances, tire tolerances, etc, so most BMW speedometers will typically be 2.4 mph + 5% high. The high reading is intentional, due to the high penalties for reading low.

The odometer is not subject to the same regulations, and is therefore designed to be accurate.

The speedometer is not adjustable.

Good thread here, with a link to the BMW TSB.

http://www.xoutpost.com/bmw-sav-foru...naccuracy.html

[rh71]

what size wheels/tires are you on? That has an effect which causes a few mph discrepancy too. Some wheel sites will show you a chart on this.

[evolver]

JCL, it is a great link that you gave. I did not realize that car manufacturers go to that length to estimate the difference in the rotational speed of wheels on snowy roads. I bet it somehow factored into the ABS and traction control programs.

rh71, I run standard size tire for the 214 style wheels. They are Vredesteins, not OEM. So there could be a little discrepancy but not by much.

[E70 Sandy Springs]

Hi,
I'm brand new here and just bought and drove about 400 miles back home in my new (to me, now with 7k) 2011 X5 today. I have a trusty GPS that I've used in our cars for a couple years now with a slight amount of error, maybe 81 on the speedo is really 80. So I'm driving home today and notice that I have to do "84" BMW Mph to get 80 GPS mph. It looks like 5% at every speed

I've got the fat 214 20" rims and big tires and wonder, just tonight driving home, if some setting needs to be changed for the diameter of the wheel and rubber. Is this option out there at all? Still a blast to drive but I need to know how fast I am going. 120 wasn't really 120 today...
Cheers!

[JCL]

See my post #5, above.

It is not adjustable. 4 mph is actually pretty close. Either consider it a safety buffer for unexpected encounters with law enforcement officers, or decide to drive 4 mph over at that speed.