Speedometer is off. Any way to adjust?
 

I have noticed over the last few weeks that my speedometer is off by a few miles per hour. When I am going 75 the needle shows 80. Also the digital trip miles is working in conjuction with the incorrect needle readout. I know this because the aftermarket GPS shows my speed and the tenth value is a little off. Also when I go through the radar speed readout through the toolbooth shows I'm going slower than what my needle shows.

With this issues it will make it seem like I have more mileage than the X has really traveled.

Thanks all.

IF the speedometer is anything like the E39.. the higher mph you go, the more you will be off.(this was also proven via GPS) But 75/80 seems a tad too unlevel.
That or you have an other problem.

Normal observation, imo...
all of us have the same situ, speedo-wise, though I recall many
comments on the odometer being accurate, as in "not exactly
connected" to the optimistic speedo reading.

From Search Tab:

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

GL,mD

Not sure about BMW but VW/Audi/Seat/Skoda can have the accuracy improved by a correction factpor being applied by the dealer. I had a speedo replaced a few years back and the unit was over-reading by about 15% so the dealer 'corrected' it to within 2mph at 70mph. The change was made by changing a value in the ECU/Vehicle instruments computer or whatever system actually drives the speedo itself (not the wheel speed sensor which is just the input device).

In the UK speedos are allowed to over-read but never under-read with the limit being set at 10% +/-2mph @ 30mph on a calibrated test system.

My speedo indication is about +3mph @ 70mph when compared to a GPS system.

I read somewhere that the speedo cannot be accurate throughout the speed range. Meaning that if it is right at 100 mph it will most likely be wrong at 30 and vice-versa.

Also, you must consider the condition of the tires and how much tread has been worn off.

I used to check my speedo in all my cars against the mile markers on the highway and kept a conversaion factor in mind for each car.

Now, I just use the gps monitor to tell me the speed I am traveling - although I know is also off, but at least it is not dependent on the car/tires.

It's not a big deal since I know it is not accurate and I know by how much. I just thought there as a way to wasily fix the issue.

BTW - My tires are new and OEM size so I it can only get worse when the tires wear.

Oh well. I guess the only time it will make a diff is on resale when I reach 100k. The 100k seems to scare peope and a 95k mile care seems to get better value than 100k. So if its off by 5% then then I will get to 100k mile 5k miles earlier. No biggie since I drive 7k miles a yr and I have 48k right now on my 03 X. At that point the X will be worth $3k resale anyway.

I don't believe that in the slightest. If you use the OBC to read your speed, it is dead on and the needle is innacurate. The days of cable speedos are long gone, it's all feed by electronic sensors at the wheel. Unfortunately, BMW has been doing this for years, and there are varying opinions all over as to why they still do this. I don't know if there is a way to correct it, so in the meantime I break the law daily by going 5mph over, knowing in reality from the OBC and my GPS that I'm really only doing like 2-3 over.

Odometers tend to be more accurate than the speedo, I doubt you will have more than a 1% error in the odometer reading. Speedos over read slightly as most countries stipulate that the speedo may not under read at all, but may over read a little. Manufacturers therefore tend to err on the side of caution and make all their speedos over read slightly.

Did you happen to change to non-stock size tires? I know, obvious, but just throwing it out there.

It's all about the lawyers. I can back up those who say that the odometer is more accurate than the speedo. Most manufacturers make the speedo read about 2 mph high around 70, from all the data I have collected with GPS devices in rental cars over the years. It keeps the automakers out of trouble.

i have considered getting tires that is a size bigger. Will I wear out or damage anything by doing so?

What do you mean by "a size bigger"?
What tire size do you currently have and what size(s)
are you considering?

No "damage" that I am aware of, with "+1" sizing...
some size "ups" may affect your speedo even more than
the std optimism.

A couple of Tire size Comparo Charts:
Tire size calculator

Tire Size Calculator - tire & wheel plus sizing

GL, mD

The trouble with upsizing the tyre is that your hytherto reasonably accurate odometer will now potentially under read. It is better to just understand that your speedo overreads by a few percent and compensate for it when driving.

I agree. Changing tire sizes in order to get the (innacurate) speedo to work will throw off your odomter and OBC (both accurate), so you're not really gaining anything. I know in my M5 I can change the percentages through the OBC for adjusting the MPG averaging. It's a software thing that controls our speedo's as well since they're not old school cables anymore, so there simply has to be a way to change some value in the computer. People are doing the somewhat complex job of coding (myself included) 740iL's into euro 740i's for 6spd conversion, so there must be a screen somewhere to change the accuracy/offset of the speedo.