Speedometer seems off.

[Raine]

Hi, does anyone else have a problem w/ their speedometer?

My speedometer seems a bit off...when I'm going 87 mph (or 140km/hr), it certainly doesn't feel like I'm going that fast, it feels more like 84 mph (or 135km/hr).

When I'm driving 87mph (140km/hr), some people infront of me seem to be driving 93 mph (150km/hr), which I highly doubt as you get fined $10,000 and get your car impounded/license suspended past that speed.

If it helps, my tire size is 18" 263 style.

[Sylon]

Have a friend roll with you, right next to you, at different speeds. Compare speedos.

Pick a friend with an unmodified car, or at least with stock wheels and tires.

[1speedbike]

It reads high, somewhere around 5%, maybe a little more. You're not going crazy or anything, it's made that way on purpose

[Raine]

Originally Posted by 1speedbike

It reads high, somewhere around 5%, maybe a little more. You're not going crazy or anything, it's made that way on purpose

Ohh ok =) It just felt weird going 87mph and having mini vans tail me =(

Is it possible for the dealership to recalibrate it?

[1speedbike]

I think it's done on purpose to have some sort of margin of error because of liability issues. The car company might get sued in the case of a crash, or getting pulled over, if their speedo was exact or even underestimating the speed, so they give themselves some room for error by overestimating. I doubt they'd correct this :/

Different manufacturers have different amounts of overestimation. I think Ford has very little, while our cars are about 5%. I usually tell myself 79 is about 75, but I'm not sure how accurate that is, it just is convenient. Hope this helps..

Sorry about it man..

[rsjean]

The police have installed one of those speed displays on the street near me. It's been there for about 2 weeks. I check it against my speedo every day at different speeds and it always seems to read about 7% over what the sign displays.

[banglemangle]

2 words...

Tom Tom

[ptack]

Are you still running stock tires? If everything is stock you might want to have someone else pace you on the highway. If there's definitely a significant difference, have the dealer fix it.

[TMR013]

Originally Posted by 1speedbike

It reads high, somewhere around 5%, maybe a little more. You're not going crazy or anything, it's made that way on purpose

Really? If that's true, you may have invalidated every speeding ticket ever written.
Where did you learn this?
It seems that the best case for OEM's would be to make it as accurate as possible to avoid any sort of liability. I would think an artificial buffer would really open them up to trouble, "Your Honor please dismiss this ticket because I have no idea what my speed was because BMW purposely makes my speedometer inaccurate". Far fetched I know, but it could create reasonable doubt.

[Raine]

Originally Posted by TMR013

Really? If that's true, you may have invalidated every speeding ticket ever written.
Where did you learn this?
It seems that the best case for OEM's would be to make it as accurate as possible to avoid any sort of liability. I would think an artificial buffer would really open them up to trouble, "Your Honor please dismiss this ticket because I have no idea what my speed was because BMW purposely makes my speedometer inaccurate". Far fetched I know, but it could create reasonable doubt.

I did some research and read there's some law in Germany where the speedometer can NEVER read below the actual speed so apparently all German car manufacturers adjust their speedometers with a buffer to avoid lawsuits. Gotta google it for more specifics.

And my friends thought I was crazy when I said it doesn't "feel" like I'm going 87mph...My father's 530i is guilty of this as well.

[JasonCSU]

Originally Posted by TMR013

Really? If that's true, you may have invalidated every speeding ticket ever written.
Where did you learn this?
It seems that the best case for OEM's would be to make it as accurate as possible to avoid any sort of liability. I would think an artificial buffer would really open them up to trouble, "Your Honor please dismiss this ticket because I have no idea what my speed was because BMW purposely makes my speedometer inaccurate". Far fetched I know, but it could create reasonable doubt.

Yes, it is true. Most of us have discovered that the speedometer reads high by comparing to a GPS, or one of those roadside speed displays that the police setup. When I was on the autobahn, I hit an indicated 150mph, but my Garmin GPS showed 144mph.

[Sylon]

Originally Posted by TMR013

Really? If that's true, you may have invalidated every speeding ticket ever written.
Where did you learn this?
It seems that the best case for OEM's would be to make it as accurate as possible to avoid any sort of liability. I would think an artificial buffer would really open them up to trouble, "Your Honor please dismiss this ticket because I have no idea what my speed was because BMW purposely makes my speedometer inaccurate". Far fetched I know, but it could create reasonable doubt.

First off, you couldn't invalidate the speeding tickets because your speedo reads high, because you would be driving under the false impression that you were going faster than you actually were, but instead you were actually driving slower in reality.

So, the only traffic violation you could try to get out of is if you were ticketed for going too slow.

[JimD]

Mine is almost exactly 3mph off at 55-60mph. According to my math, going up from a 225/45 to a 225/50 rear tire would just about calibrate it (if it fits).

I have a Garmin 885t in the mount BMW sells for the similar Plus/Pro accessories so it resides just to the right of the instruments. I seldom look at the speedometer anymore because I get disgusted by deliberately false readings. The GPS is what I use for indication of my speed. I do not really care what BMWs excuse is, this is stupid. Much worst to me than run flat tires and no dipstick. At least there is some advantage to me of the tires and electronic oil level indication. I see no advantage of an inaccurate speedometer. All it would take is changing the software so the dealers could set the tire size to let it be accurate. Even cheap brands manage to figure this out.

Jim

[JimD]

This is a link to the applicable Wikepedia article:

http://en.wikipedia.org/wiki/Speedometer

It says that the manufacturer is allow 10% + 4km/h error in Europe and you can't indicate slower than the car is going. It further says that the maximum error in the U. S. is 5%. So BMW easily meets the European requirement and barely meets the U. S..

Seems like the U. S. should change our law to 1%. With it being electronic, everybody can easily do it. I'd pay a little more to get an accurate speedometer. It looks like in this area, BMW is only willing to do the legal minimum.

Jim

[TMR013]

Originally Posted by JimD

Mine is almost exactly 3mph off at 55-60mph. According to my math, going up from a 225/45 to a 225/50 rear tire would just about calibrate it (if it fits).

I have a Garmin 885t in the mount BMW sells for the similar Plus/Pro accessories so it resides just to the right of the instruments. I seldom look at the speedometer anymore because I get disgusted by deliberately false readings. The GPS is what I use for indication of my speed. I do not really care what BMWs excuse is, this is stupid. Much worst to me than run flat tires and no dipstick. At least there is some advantage to me of the tires and electronic oil level indication. I see no advantage of an inaccurate speedometer. All it would take is changing the software so the dealers could set the tire size to let it be accurate. Even cheap brands manage to figure this out.

Jim

+1

[HPFREAK]

The stock speedo does read a few mph fast. I have a vbox and it consistantly shows 3-4 mph off. It is actually a good thing when being gunned by the police with radar. it will show them you are going slower than you think you are. Maybe it is a BMW feature to help avoid tickets, I am not sure

[Bimmer-Bob]

Originally Posted by Raine

My speedometer seems a bit off...when I'm going 87 mph (or 140km/hr), it certainly doesn't feel like I'm going that fast, it feels more like 84 mph (or 135km/hr).

Are you kidding me? You're saying you can feel a difference between 84 mph and 87 mph?

[FJUNO78]

Originally Posted by Raine

when I'm going 87 mph (or 140km/hr), it certainly doesn't feel like I'm going that fast, it feels more like 84 mph (or 135km/hr).

[Tom K.]

Originally Posted by Raine

I did some research and read there's some law in Germany where the speedometer can NEVER read below the actual speed so apparently all German car manufacturers adjust their speedometers with a buffer to avoid lawsuits.

That is true, but not all BMW speedos read equally high as some would have you believe. On 4 different BMW autos, I've observed errors ranging from 5% optimistic to accurate within 1%.

You can easily check yours with either a GPS or the car's OBC.

Tom

[jeremyc74]

Originally Posted by JimD

This is a link to the applicable Wikepedia article:

http://en.wikipedia.org/wiki/Speedometer

It says that the manufacturer is allow 10% + 4km/h error in Europe and you can't indicate slower than the car is going. It further says that the maximum error in the U. S. is 5%. So BMW easily meets the European requirement and barely meets the U. S..

Seems like the U. S. should change our law to 1%. With it being electronic, everybody can easily do it. I'd pay a little more to get an accurate speedometer. It looks like in this area, BMW is only willing to do the legal minimum.

Jim

It's not a matter of it costing more to be accurate. The car knows exactly how fast it's going, it's just displaying a speed that's faster than actual speed. If you plug into it with a diagnostics tool you'll see two speed displays, "Actual" and "Displayed". The actual speed is extremely accurate, but they're adding error to it for display to the driver.


They probably take the smallest tire size the car is available with, with absolute maximum wear, and then add a margin of safety to that to come up with the error they induce to make absolutely sure they don't display a speed that's below actual. The end result is a speedometer that's noticably inaccurate with normal tires on the car.

I don't like it at all either. My previous car was less than 1Mph off from the GPS, and I don't see any reason BMW needs these huge display errors on modern vehicles.

[Mega Man]

This car and my last car all read faster than I'm currently traveling. I think it's for safety purposes. If you think you're going faster than you are because your speedo says so, you'll travel a bit slower.

[bozola]

My data.....

Garmin - 80
Passport 9500ix - 80
Speedometer - 83