Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

Please follow the links below to help get you started!

Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E90/E91/E92/E93 (2006 - 2013)

E90/E91/E92/E93 (2006 - 2013)
The E9X is the 4th evolution of the BMW 3 series including a highly tuned twin turbo 335i variant pushing out 300hp and 300 ft. lbs. of torque. BMW continues to show that it sets the bar for true driving performance! -- View the E9X Wiki

Reply
 
Thread Tools Display Modes
  #1  
Old 08-29-2007, 09:36 AM
ajfinoak ajfinoak is offline
Officially Welcomed to the 'Fest
Location: Oakland, CA
 
Join Date: Jul 2006
Posts: 108
Mein Auto: '06 BMW 325i '01 Acura CL
Speedometer Calibration

I was reading the long term review of the '06 330 in Car and Driver last month and it said that the speedometer is over by 4 mph. Anyone else think (or know) if theirs is off? On SF Bay Area highways, I seem to be passing a lot more people at 80 mph in my Acura than at 80 in the BMW. How can one check?
Reply With Quote
Advertisement
  #2  
Old 08-29-2007, 09:39 AM
BMW Power's Avatar
BMW Power BMW Power is offline
Officially Welcomed to the 'Fest
Location: Boston, MA
 
Join Date: Jul 2007
Posts: 1,503
Mein Auto: 2012 X5 35d
You can use a portable GPS and look at the speed there. BMW speedometers are optimistic, it gets worse with higher speed. There has been some discussion of this before.
__________________
2012 X5 35d DSB - Prem, SAV, Cold, Sound, Tech packages, Apps Delivered 6/6/12

Retired 2011 335d AW, M Sport, Premium and Convenience pkg, Heated Seats, Nav, HK, iPod/USB, smart phone. ED 8/31/10

Retired 2008 335i Coupe 6-speed Manual, Montego Blue, Sport, Premium, CW, Nav, PDC, AS, Shade, HD, Sat, Ipod/USB, Logic 7, CA
PCD 11/07

Retired 2004 545i Sapphire Black/Black 6-speed Manual, Sport.
Reply With Quote
  #3  
Old 08-29-2007, 10:02 AM
ajfinoak ajfinoak is offline
Officially Welcomed to the 'Fest
Location: Oakland, CA
 
Join Date: Jul 2006
Posts: 108
Mein Auto: '06 BMW 325i '01 Acura CL
Sorry- just did a search and realized it is just something that needs to be accepted about the car. Maybe I will save myself from a ticket while deluding myself that I am speeding.
Reply With Quote
  #4  
Old 08-29-2007, 03:38 PM
VIZSLA's Avatar
VIZSLA VIZSLA is offline
Officially Welcomed to the 'Fest
Location: North of Boston south of Tampa
 
Join Date: Mar 2007
Posts: 1,283
Mein Auto: 328 328 308
Quote:
Originally Posted by BMW Power View Post
You can use a portable GPS and look at the speed there. BMW speedometers are optimistic, it gets worse with higher speed. There has been some discussion of this before.
GPS units do not have sufficient accuracy (the margin of error is at best twenty feet and can be well over one hundred) to use as a speedometer. Useing mile markers and a stop watch is about the best measure. At sixty mph you'll pass one mile every sixty seconds. Any decent stop watch will have a tachymeter in the bezel to do the math for you.
Reply With Quote
  #5  
Old 08-29-2007, 04:08 PM
bufasion bufasion is offline
Officially Welcomed to the 'Fest
Location: RNO
 
Join Date: Oct 2006
Posts: 175
Mein Auto: 328xi
Quote:
Originally Posted by VIZSLA View Post
GPS units do not have sufficient accuracy (the margin of error is at best twenty feet and can be well over one hundred) to use as a speedometer...
Typical GPS units use more than just position data to calculate speed. The spec for velocity error on Nuvi is 0.05m/s RMS, which translates to about 0.11 mph.

http://gpsinformation.net/main/gpsspeed.htm

Last edited by bufasion; 08-29-2007 at 04:20 PM.
Reply With Quote
  #6  
Old 08-29-2007, 04:10 PM
Tanning machine's Avatar
Tanning machine Tanning machine is offline
Using SPF 45
Location: Washington, D.C.
 
Join Date: Feb 2002
Posts: 3,519
Mein Auto: 2004 330Cic
Quote:
Originally Posted by VIZSLA View Post
Useing mile markers and a stop watch is about the best measure. At sixty mph you'll pass one mile every sixty seconds. Any decent stop watch will have a tachymeter in the bezel to do the math for you.
This is good (no idea on GPS). I've done it before, and my BMW seems to be about 7% over the actual speed. That's way more than any other car I've driven.
__________________
Tanning Machine I: 1989 325iC (Salmon Silver/Black, Heated Seats, LSD). 7/26/1989-11/1/2003.
Tanning Machine II: 2004 330Cic (Silver Gray/Natural Brown, SP, PP, Heated Seats, Xenons). 8/29/2003-present.
Reply With Quote
  #7  
Old 08-29-2007, 04:14 PM
VIZSLA's Avatar
VIZSLA VIZSLA is offline
Officially Welcomed to the 'Fest
Location: North of Boston south of Tampa
 
Join Date: Mar 2007
Posts: 1,283
Mein Auto: 328 328 308
Quote:
Originally Posted by bufasion View Post
GPS units usually use more than just position data to calculate speed. The spec for velocity error on Nuvi is 0.05m/s RMS, which translates to about 0.11 mph.
What data beside change of position over time can yield speed? If position starts as an aproximate any resulting calculation will have the same aproximation in its result. The Nuvi stats sound like they relate to processing accuracy not positional.
Reply With Quote
  #8  
Old 08-29-2007, 05:41 PM
bufasion bufasion is offline
Officially Welcomed to the 'Fest
Location: RNO
 
Join Date: Oct 2006
Posts: 175
Mein Auto: 328xi
Doppler shift. See http://gpsinformation.net/main/gpsspeed.htm

From the NAVSTAR GPS User Equipment Introduction document Section 3.7:

GPS receivers typically calculate velocity by measuring the frequency shift (Doppler shift) of the GPS D-band carrier(s). Velocity accuracy can be scenario dependent, (multipath, obstructed sky view from the dash of a car, mountains, city canyons, bad DOP) but 0.2 m/sec per axis (95%) is achievable for PPS and SPS velocity accuracy is the same as PPS when SA is off.

Velocity measured by a GPS is inherently 3 dimension, but consumer GPS receivers only report 2D (horizontal) speed on their readout. Garmin's specifications quote 0.1mph accuracy but due to signal degredation problems noted above, perhaps 0.5mph accuracy in typical automobile applications would be what you can count on....

Last edited by bufasion; 08-29-2007 at 05:47 PM.
Reply With Quote
  #9  
Old 08-29-2007, 06:07 PM
VIZSLA's Avatar
VIZSLA VIZSLA is offline
Officially Welcomed to the 'Fest
Location: North of Boston south of Tampa
 
Join Date: Mar 2007
Posts: 1,283
Mein Auto: 328 328 308
Quote:
Originally Posted by bufasion View Post
Doppler shift. See http://gpsinformation.net/main/gpsspeed.htm

From the NAVSTAR GPS User Equipment Introduction document Section 3.7:

GPS receivers typically calculate velocity by measuring the frequency shift (Doppler shift) of the GPS D-band carrier(s). Velocity accuracy can be scenario dependent, (multipath, obstructed sky view from the dash of a car, mountains, city canyons, bad DOP) but 0.2 m/sec per axis (95%) is achievable for PPS and SPS velocity accuracy is the same as PPS when SA is off.

Velocity measured by a GPS is inherently 3 dimension, but consumer GPS receivers only report 2D (horizontal) speed on their readout. Garmin's specifications quote 0.1mph accuracy but due to signal degredation problems noted above, perhaps 0.5mph accuracy in typical automobile applications would be what you can count on....
Thanks for the backround. Hadn't occured to me that that Herr Dopler would be involved.
As an aside the Garmin will register higher speeds than the article indicated. My Max speed is 611 MPH. Done not in a BMW but a Boeing.
Reply With Quote
  #10  
Old 08-29-2007, 06:14 PM
BMW Power's Avatar
BMW Power BMW Power is offline
Officially Welcomed to the 'Fest
Location: Boston, MA
 
Join Date: Jul 2007
Posts: 1,503
Mein Auto: 2012 X5 35d
I have also used the "Your Speed is" radar signs the local police put up.
__________________
2012 X5 35d DSB - Prem, SAV, Cold, Sound, Tech packages, Apps Delivered 6/6/12

Retired 2011 335d AW, M Sport, Premium and Convenience pkg, Heated Seats, Nav, HK, iPod/USB, smart phone. ED 8/31/10

Retired 2008 335i Coupe 6-speed Manual, Montego Blue, Sport, Premium, CW, Nav, PDC, AS, Shade, HD, Sat, Ipod/USB, Logic 7, CA
PCD 11/07

Retired 2004 545i Sapphire Black/Black 6-speed Manual, Sport.
Reply With Quote
  #11  
Old 08-29-2007, 06:20 PM
crowz's Avatar
crowz crowz is offline
Officially Welcomed to the 'Fest
Location: Alabama
 
Join Date: Oct 2006
Posts: 4,560
Mein Auto: 2000 323i, 97 528i
Thats pretty accurate though as far as car speedometers go. So Id take the gps as the best way to determine how accurate the speedometer is.
Reply With Quote
  #12  
Old 08-29-2007, 06:32 PM
Fast Bob's Avatar
Fast Bob Fast Bob is offline
Keeping it surreal
Location: Here, there, everywhere....
 
Join Date: Jun 2004
Posts: 35,013
Mein Auto: 2004 330Ci ZHP 3 pedals
While not definitive by any means, you can also use the car`s OBC.... put it in the AVG. MPH function, and on a clear stretch of highway, set your cruise control exactly on a speedo-indicated 60 mph. Then zero out the OBC while on the cruise control, and compare the speedo`s reading to the OBC reading. Of course, the farther you drive, the more accurate your average reading will become. You can increase your speed in 10 MPH increments to see if the error rate increases with rate of speed.

Regards,
Bob
Reply With Quote
  #13  
Old 08-29-2007, 06:40 PM
Ruff Rider's Avatar
Ruff Rider Ruff Rider is offline
Officially Welcomed to the 'Fest
Location: Mountains
 
Join Date: Dec 2006
Posts: 163
Mein Auto: A bicycle
Just lick your finger. Stick it out the window. If it dries in 3 seconds your going 62mph. Works 60% of the time every time.
__________________

[SIGPIC][/SIGPIC]

Last edited by Ruff Rider; 08-29-2007 at 06:55 PM.
Reply With Quote
  #14  
Old 08-29-2007, 06:54 PM
bufasion bufasion is offline
Officially Welcomed to the 'Fest
Location: RNO
 
Join Date: Oct 2006
Posts: 175
Mein Auto: 328xi
Quote:
Originally Posted by VIZSLA View Post
As an aside the Garmin will register higher speeds than the article indicated. My Max speed is 611 MPH. Done not in a BMW but a Boeing.
I think most GPS has a limit at 999 mph. My max ground speed is 185 mph, not in a BMW but in a train. Max speed in my 328xi is only 129 mph (4600 rpm in 6th or 5900 in 5th). The speedo indicated 136 mph.
Reply With Quote
  #15  
Old 08-30-2007, 02:38 AM
Briar Briar is offline
Officially Welcomed to the 'Fest
Location: Nor Cal
 
Join Date: May 2007
Posts: 131
Mein Auto: 335i. 996 Cab
I have tested my 335I versus a garmin and the 335i is consistently indicating 3 mph over the garmin, from 30 - 90 mph. Error is less below 30 mph, but not able to quatify.
Comparing distance traveled is less than 1%, for trips over 30 miles.
Reply With Quote
  #16  
Old 08-30-2007, 09:37 AM
BMW Power's Avatar
BMW Power BMW Power is offline
Officially Welcomed to the 'Fest
Location: Boston, MA
 
Join Date: Jul 2007
Posts: 1,503
Mein Auto: 2012 X5 35d
Quote:
Originally Posted by Briar View Post
I have tested my 335I versus a garmin and the 335i is consistently indicating 3 mph over the garmin, from 30 - 90 mph. Error is less below 30 mph, but not able to quatify.
Comparing distance traveled is less than 1%, for trips over 30 miles.
The odometers are supposed to be acurate, otherwise warranty would run out early. Honda just extended their warranty mileage by 5% because the odometers were off on certain vehicles.
__________________
2012 X5 35d DSB - Prem, SAV, Cold, Sound, Tech packages, Apps Delivered 6/6/12

Retired 2011 335d AW, M Sport, Premium and Convenience pkg, Heated Seats, Nav, HK, iPod/USB, smart phone. ED 8/31/10

Retired 2008 335i Coupe 6-speed Manual, Montego Blue, Sport, Premium, CW, Nav, PDC, AS, Shade, HD, Sat, Ipod/USB, Logic 7, CA
PCD 11/07

Retired 2004 545i Sapphire Black/Black 6-speed Manual, Sport.
Reply With Quote
  #17  
Old 08-30-2007, 11:11 AM
AzNMpower32's Avatar
AzNMpower32 AzNMpower32 is online now
Tar Heel Faithful
Location: WNC
 
Join Date: Oct 2005
Posts: 14,011
Send a message via AIM to AzNMpower32
Mein Auto: 2014 Mazda3 GT
I believe deep inside the computer system, the BMW knows the true speed. However, the speedometer is a fraction off. I read somewhere that for almost any analog speedometer, the error gets worse as speeds increase. The X3 is about 3% off.
Reply With Quote
  #18  
Old 08-30-2007, 11:11 AM
jwac's Avatar
jwac jwac is offline
Officially Welcomed to the 'Fest
Location: San Francisco Bay Area
 
Join Date: Dec 2006
Posts: 2,680
Mein Auto: '14 335i 6MT
I've heard about this BMW phenomenom for a long time, but the question I have is why? Obviously they're able to calibrate exactly but choose not to.

The explanation I've heard is that BMW believes many of its customers switch to different-sized wheels in the aftermarket, so they're protecting the speedometer from under-reading if the customer does not have the car recalibrated. Any truth to this?
__________________
2014 335i Sedan 6MT
Estoril Blue | Black leather | Dark Burl Walnut
M Sport | Premium | Driver Assistance Plus | Technology | Dynamic Handling | Cold Weather | 19" 403M Wheels | M Sport Brakes | Harman Kardon | Rear Window Shades | Auto High Beams

09.16.13 European Delivery

Past:
2011 335i Coupe 6MT (ED)
2010 135i Vert 6MT (ED)
2007 335i Coupe 6MT (ED)

2006 325i Sedan 6MT
Reply With Quote
  #19  
Old 08-30-2007, 12:06 PM
Chuckycheese Chuckycheese is offline
Registered User
Location: California
 
Join Date: Feb 2006
Posts: 80
Mein Auto: 2006 BMW 325xi
Cool I checked!

I've checked mine with a GPS and also the highway radar checks and have found that when the speedometer shows 70MPH...I'm really going 66MPH. An earlier post said the difference is 4MPH and that's exactly what I've found. (I suppose it's less at 30MPH.)
Reply With Quote
  #20  
Old 08-30-2007, 01:35 PM
ek_335i ek_335i is offline
Officially Welcomed to the 'Fest
Location: FL
 
Join Date: Jul 2006
Posts: 205
Mein Auto: 335i Sedan
Quote:
Originally Posted by BMW Power View Post
The odometers are supposed to be acurate, otherwise warranty would run out early. Honda just extended their warranty mileage by 5% because the odometers were off on certain vehicles.
The odometer is accurate. The speedometer is not. You can have an accurate odometer and an inaccurate speedometer.

Ed
__________________
2007 e90 335i - Delivered 10/7/2006
Sparkling Graphite | Black Leather | Burl Walnut Wood Trim | Premium Package | Sport Package | Steptronic | Paddle Shifters | Navigation | Park Distance Control
Reply With Quote
  #21  
Old 08-30-2007, 01:52 PM
BMW Power's Avatar
BMW Power BMW Power is offline
Officially Welcomed to the 'Fest
Location: Boston, MA
 
Join Date: Jul 2007
Posts: 1,503
Mein Auto: 2012 X5 35d
Quote:
Originally Posted by ek_335i View Post
The odometer is accurate. The speedometer is not. You can have an accurate odometer and an inaccurate speedometer.

Ed
Right, that's what I said.
__________________
2012 X5 35d DSB - Prem, SAV, Cold, Sound, Tech packages, Apps Delivered 6/6/12

Retired 2011 335d AW, M Sport, Premium and Convenience pkg, Heated Seats, Nav, HK, iPod/USB, smart phone. ED 8/31/10

Retired 2008 335i Coupe 6-speed Manual, Montego Blue, Sport, Premium, CW, Nav, PDC, AS, Shade, HD, Sat, Ipod/USB, Logic 7, CA
PCD 11/07

Retired 2004 545i Sapphire Black/Black 6-speed Manual, Sport.
Reply With Quote
  #22  
Old 08-30-2007, 02:00 PM
iversonm's Avatar
iversonm iversonm is offline
3 pedals only!
Location: Grosse Ile, Michigan
 
Join Date: Nov 2004
Posts: 2,666
Mein Auto: 2008 550i Carbon Black
Quote:
Originally Posted by jwac View Post
I've heard about this BMW phenomenom for a long time, but the question I have is why?
EU Regulations, that more or less state that a speedometer can never read low, regardless of the exact brand of tire on the car, etc.

Therefore, they aim for about 3-5% high.
__________________
2012 E88 128i, Alpine White/Black
2011 E90 328i, Crimson Red/Black
2008 E60 550i, Carbon Black/Natural Brown, ED 2 November 2007 (retired)
2006 E83 X3, Silver Grey/Black, ED 15 May 2006. (retired)
2005 E46 330i, Jet Black/Black (retired)
2002 E46 325i, Electric Red/Black (retired)
Reply With Quote
  #23  
Old 09-01-2007, 08:24 PM
paraboloid paraboloid is offline
Officially Welcomed to the 'Fest
Location: Earth
 
Join Date: Feb 2006
Posts: 167
Mein Auto: BMW
Quote:
Originally Posted by iversonm View Post
EU Regulations, that more or less state that a speedometer can never read low, regardless of the exact brand of tire on the car, etc.

Therefore, they aim for about 3-5% high.
Are sure about that? Why doesn't Volvo follow the EU Regulation? It has almost 100% accurate speedometer. Maybe BMW wants to make a virtual impression of the ultimate driving machine. You think you drive fast, but a guy in Volvo thinks you are a slow driver. I hope CarAndDriver didn't use BMW's speedometer for 0-60 time measurements . It's sad that none of the auto magazines reported about the speedometer's inaccuracy in different cars.
Reply With Quote
  #24  
Old 09-01-2007, 08:55 PM
jwac's Avatar
jwac jwac is offline
Officially Welcomed to the 'Fest
Location: San Francisco Bay Area
 
Join Date: Dec 2006
Posts: 2,680
Mein Auto: '14 335i 6MT
Quote:
Originally Posted by paraboloid View Post
Are sure about that? Why doesn't Volvo follow the EU Regulation? It has almost 100% accurate speedometer. Maybe BMW wants to make a virtual impression of the ultimate driving machine. You think you drive fast, but a guy in Volvo thinks you are a slow driver. I hope CarAndDriver didn't use BMW's speedometer for 0-60 time measurements . It's sad that none of the auto magazines reported about the speedometer's inaccuracy in different cars.
If what I've heard is true, it could be because Volvo owners don't necessarily swap out wheels/tires with different sizes as much as BMW owners do. So Volvo doesn't need the speedometer contingency plan.

The mags don't watch the speedometer with a stopwatch for their timed acceleration runs. At least I hope none of them do! Many use some form of an independent data capture device, like a GPS-based Racelogic VBOX (Edmunds) or a Datron optical "fifth wheel" (C&D, last I heard).
__________________
2014 335i Sedan 6MT
Estoril Blue | Black leather | Dark Burl Walnut
M Sport | Premium | Driver Assistance Plus | Technology | Dynamic Handling | Cold Weather | 19" 403M Wheels | M Sport Brakes | Harman Kardon | Rear Window Shades | Auto High Beams

09.16.13 European Delivery

Past:
2011 335i Coupe 6MT (ED)
2010 135i Vert 6MT (ED)
2007 335i Coupe 6MT (ED)

2006 325i Sedan 6MT
Reply With Quote
  #25  
Old 09-01-2007, 10:17 PM
paraboloid paraboloid is offline
Officially Welcomed to the 'Fest
Location: Earth
 
Join Date: Feb 2006
Posts: 167
Mein Auto: BMW
Quote:
Originally Posted by jwac View Post
If what I've heard is true, it could be because Volvo owners don't necessarily swap out wheels/tires with different sizes as much as BMW owners do. So Volvo doesn't need the speedometer contingency plan.
Do you really think BMW makes an inaccurate speedometer, because one crazy guy from ten thousand people will install bigger wheels? Isn't it the owner's responsibility to recalibrate the speedometer in a car with bigger wheels?
Reply With Quote
Reply

Bookmarks


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E90/E91/E92/E93 (2006 - 2013)
Today's Posts Search
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



Forum Jump


All times are GMT -7. The time now is 06:19 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
© 2001-2011 performanceIX, Inc. All Rights Reserved .: guidelines .:. privacy .:. terms