BMW 3-Series Speedometer Inaccuracy

330cic

I've noted that my speedometer is reading 3-4 mph faster than my indicated speed on my GPS. Anyone else noted this descrepancy? If the speedo isn't tracking accurately, especially reading faster and putting miles on the odometer faster, this will make my warranty expire faster. At best it'll keep me from going over the posted speed limit, if I fix my speed, via the speedo, at the posted speed limit.

kominsky

That is very common. I'm pretty sure that it's done for liability purposes, but don't quote me on it.

I see it with my 330Ci, my wife's current Odyssey, and her previous Odyssey.

To the best of my knowledge, most/all auto and motorcycle manufacturers build in some amount of slop. Some motorcycle magazines quote actual speed at an indicated 60mph in their stats (ALWAYS lower than 60mph). I believe auto mags used to do it too, but stopped some time ago for whatever reason.

I have no idea if it racks up miles faster than what is real or not.

330cic

I've found that in my Toyota 4Runner that the speedometer tracks right along with the GPS.

The problem with a speedometer reading inaccuratly is that the number of miles on the odometer would be directly affected as well. For example, if the speedo is 3 mph too fast, the number of miles on the odomenter would be accululating at that rate as well. This will affect the length of your warranty (it would run out faster). Not a good thing at all. If BMW has built in a fudge factor of the speedo registering fasr than one is really going, and piling on mileage on the odomenter at a faster rate, that smacks of consumer fraud,

shipo

While BMW speedometers typically register high, their odometers are usually dead-on-balls-accurate (it's an industry term). ;-)

Best Regards,
Shipo

330cic

Well damn. That stinks that they'd register higher than actual speed. While I know that on boats that's pretty well a known "problem", that's typically because of factors such as waves, etc., interfering with accuracy. On an auto, I'd think it shouldn't be.

I did take the car in to have that looked at, so I guess I'll have some kind of response from the dealer when I pick it up.

idoc2

I drive a 2007 328xi. The speedometer reads about 6% faster than either of two Garmin GPS units I own. As were you I was concerned about the odometer and the implications this has for the warranty. As you undoubtedly know there was class action law suit against Honda for this. Nevertheless, I did check my odometer against one of my GPS units over about a 100 mile highway drive. As Shipo noted the odometer was absolutely accurate. It is a mystery as to why BMW (obviously knowingly) miscalibrates their speedometers. One forum member has suggested it was to get drivers to effectively drive slower, thus make speeding tickets less likely thus lower insurance premiums for their cars. Who knows?

kominsky

http://www.caranddriver.com/features/1906/speedometer-scandal.html

cinquanti

(Kominsky's article) So I guess that based on our 160mph speedo, mine reading 59 while actually traveling 65 is acceptable. This was the response from my service department:

THIS IS A FACTORY ACCEPTABLE CONDITION DUE TO THE MANY DIFFERENT TIRE AND WHEEL PACKAGES. THE STANDARD IS 10% PLUS 2.4 MPH IT SEEMS YOU ARE IN THE ACCEPTABLE RANGE ALSO BUT IF YOU GO MILE MARKER TO MILE MARKER THE ODOMETER IS RIGHT ON

All these years driving economy grade cars the speedo was so close I never noticed. Now I spring for a finely tuned precision German car and it doesn't know how fast it's going? Wow.

roadburner

All these years driving economy grade cars the speedo was so close I never noticed. Now I spring for a finely tuned precision German car and it doesn't know how fast it's going? Wow.

Yeah, it's kept me awake at night since 1983...

idoc2

Its a good thing you're such a light sleeper so you won't be inconvenienced by the expensive Swiss alarm clock you just bought that doesn't keep accurate time.

Let's not be apologists for BMW's shortcomings of which there are several (speedo inaccuracies, RFT's, no dipstick, no temp gauge ...). We should not be dismissive when members of this discussion group level legitimate criticisms. Its really totally unacceptable that my BMW's speedometer is far less accurate than my wife's Honda minivan or my 1998 Maxima. Using two GPS units my BMW consistently indicates a speed about 7% faster than true speed whereas the speedometers in the other two cars are dead on. Despite BMW justification there is really no excuse for such a basic inadequacy.

kdshapiro

But when you swap the tires on your Honda for a different size..the ending will be different.

roadburner

Its(sic) really totally unacceptable that my BMW's speedometer is far less accurate than my wife's Honda minivan or my 1998 Maxima. Using two GPS units my BMW consistently indicates a speed about 7% faster than true speed whereas the speedometers in the other two cars are dead on. Despite BMW justification there is really no excuse for such a basic inadequacy.

It's good to know that you don't sweat the small stuff.
Your last name isn't Monk, is it?

idoc2

Of course you're correct, but I always have the choice of replacing with OEM's. Nevertheless, on my wife's minivan and obviously on my 1998 Maxima I've gone thru several sets of tires (and use snow tires in the winter) and it hasn't made a noticeable difference in the speedo accuracy. I suspect that tire manufactures have industry standards with regards to dimensions when they produce tires of a specific size. Even if they don't, with my BMW I have no idea which if any available tires would exactly offset the poor calibration of the speedo as it came from the factory.

idoc2

No, but as always Dr. House we plebeian members greatly appreciate your concern for our well being and your beneficent sharing of automotive wisdom. :P Nevertheless, trivial to the apologists as it may be I still expect an accurate speedo.

cdnpinhead

I'm going to have to throw in with the anal-retentive here (big surprise -- look at my moniker). I've also noticed that my various rental cars, as well as the one I drive every day (and have for 127K miles), display a speed that is dead-on in agreement with my Garmin. Even better, at the end of a 753 mile day, the Garmin and the odometer are within a fraction of a percent. I'm a happy camper.

Now, when I get my BMW, I'm led to believe that the speed itself can be all over the map but the odometer will be dead-on. Well, I expect (demand, actually) the odometer to be right, but wonder why the "logic" that applies to the speedometer doesn't to the odometer. Those tire changes will affect the odometer as well.

What's up?

widriver2

If that is the case it probably saved me some major $ on speeding tickets.

330cic

I am in agreement that Bimmers should not register inaccurate speeds on the speedometer. The tires that I have on the car are the Conti RFT's and are the correct size for the car. They are not custom. If I had larger or smaller diameter tires and wheels on the car, the yes, I would expect for the speedo to read inacurrately. My '03 4Runner is dead on with the GPS. Don't know why BMW would think it's acceptable to not have an accurate gauge.

upstatedoc

hate to beat a dead horse here, but has anyone found a solution to the speedo inaccuracies? Mine reads 4 mph over the real speed at highway speeds. Is there something to adjust w/ the cars computer? I think I know why the 3-series didn't make the "Top 10 Most Ticketed Cars" list, everyone is doing under the speed limit. :P

bmwlemon

my wife's BMW 328i speedometer is off as well. When actually traveling 70mph it reads 75. The odometer is off too. The dealership assured me the two are not connected, but I doesn't matter. According to BMW customer service I can travel 45,000 miles and my odometer will read 50,000 thus ending my warranty. They refuse to correct this problem.

steveaccord

I am sure everyone is sleeping soundly on this topic, after all the last post goes back to 2009! That beside I do believe that assuming that the speedometer and the odometers are tracking their respective measure in a connected manner is just plain wrong. Odometers are set according to precise requirements defined by the department transportation and need to be calibrated according to actual mileage, hence the legal implications of frauds connected to resetting it by various means. To my knowledge the odometer has a hardwired cabling to the actual axle transmission sends power to. That is not necessarily the case with the speedometer where, as other have suggested, it may be BMW intention to dupe us to believe we are driving faster than we actually are. That is the case also for my 2008 335xi that clock between 4-5 miles faster than the GPS. I found no such discrepancy between the same GPS and my wife 2011 XC 60 Volvo. Also let's be clear, automotive magazines rely on vehicle outfitted with their highly precise measurement devices when reporting on actual vehicle performance so their data can be trusted and do not depend on the manufacturer onboard dials.

steveaccord

Forgot to mention. For what I could tell watching the video posted online the car speed record clocked last year (2011) on German highways on a super modified 540i may have been biased by an inaccurate reading of the odometer. That is what they were showing on the video..the speedometer reaching 237 mph. I am not sure if taking ~ 5mph away, should have they relied entirely on the speedometer reading, would still qualify that vehicle as the speed record holder.
Lastly, speaking about modified vehicles I missed to identify any 3-series related post-market mod forum. I would be interested in such discussions given that I envision to retire my 2008 335xi but keep it as a tasteful track-modded spare car but I do not even know if the AWD model is really conducive to this type of alterations (sure I hope so, F-1 cars are in fact AWD these days). Any chance the gracious Hosts would be able to start one if none is currently ongoing?

busiris

it may be BMW intention to dupe us to believe we are driving faster than we actually are.

Well, it may sound good the say that BMW is "duping" us, but the facts tell otherwise.

European standards are quite specific on the accuracy of speedometers, from a conservative perspective. That means its acceptable to show too fast a speed, but UNACCEPTABLE to show a slower-than-actual speed.

Manufacturers can still be held liable for speed differential errors, even if the car owner changes to different wheels, tires, etc., where a sizing difference would have an effect on speedometer accuracy.

That is why speeds always show faster than actual on BMW's.

For more, scroll down to the section labeled "International Agreements".

steveaccord

Thank you, I learned something I was not aware of. That would logically explain BMW point on view on overestimating speeds, although if I may point it out, raises question on why not all European manufacturer share such approach. As I quoted the discrepancy does not come up on our Volvo, another manufacturer based in Europe ( I agree owned by non European entities and not an EC member country). I think the accuracy of speedometer was reported by others in the post.....So I am still left wondering if the regulatory European aspects you raise exhaustively justify the speedometer inaccuracies.

lewd

well I just traded my mercedes in on my bmw and the mercedes speedometer was accurate so why not the bimmer?

dll66

I have a 1993 BMW 318iS. I've just got back from a trip with it and according to my GPS, the speedometer is accurate.

jc1020

if your car is a lease think about all the extra money BMW is collecting at the end of the lease if your car is registering only 5mph faster. I have that problem with my 2011 328

kyfdx

Fortunately, the odometer isn't directly connected to the needle on the speedometer... In all of the BMWs we've owned, the odometer is dead-on accurate, even though the speedometer seems to register too high...

Just my experience with it...

busiris

The subject of BMW speedo's being inaccurate (with accurate odometers) has been bludgeoned all across the Interweb. A simple Google search of "BMW speedometer inaccuracy" will show dozens of hits, many linking to official explanations.

Here's one....

http://www.caranddriver.com/features/speedometer-scandal-speedometer-scandal-pag- e-2

All I can say is that, like it or not, BMW speedo's comply with European standards and requirements for automobiles. It is what it is....