 » Site Navigation | | | | » Recent Threads | | | |  |  |  |  05-05-2009, 02:56 PM | #1 | | Member Join Date: Feb 2008 Location: Ontario, Canada Posts: 67 |  Incorrect odometer
Since i got the GPS i have found that the odometer is incorrect by a factor of 4%. i.e. If the Odometer records my speed as 100Km/hr, the GPS records it as 96km/hr.
Is this unique to my car or is this common, my research has not revealed this as no one has pointed it out (yet).
If this is a issue with my car, then what could be the cause? and how do i correct the issue?
PS: 1996 BMW 318Ti with stock suspension and stock 15" wheels with 225/60/15 summer tires.
thx |  |  | | 05-05-2009, 04:57 PM | #2 | | Senior Member Join Date: Sep 2006 Location: Wisconsin Posts: 1,895 |
You mean speedometer.
It has been my experience that most speedo's are optimistic by the percentage you mention. __________________ ...
ʎɐqǝ uo pɹɐoqʎǝʞ ɐ ʎnq ı ǝɯıʇ ʇsɐן ǝɥʇ sı sıɥʇ | | | | | 05-05-2009, 06:53 PM | #3 | | Senior Member Join Date: Apr 2007 Location: Elizabeth City, NC Posts: 3,877 |
Quote: Originally Posted by b.u.ti-ful  It has been my experience that most speedo's are optimistic by the percentage you mention. | Same. The manufacturer wants it to read higher rather than lower. If it read lower then people could sue the manufacturer for speeding tickets. Every time I have driven by one of those police trailers that tell you your speed it has been slower than what my speedo read. __________________ ~Dave~
98 328ti Morea Grun slicktop
11 128i space gray slicktop
13 JGC WK2 Deep Cherry
Search | RealOEM | | | | | 05-05-2009, 09:45 PM | #4 | | Senior Member Join Date: Apr 2008 Location: Bethlehem, PA Posts: 1,106 |
my gps did the same thing, figured it was just the gps that was wrong.. haha __________________ Check out our new website! https://soltechsolutionsllc.com/
Green Your Decor with the Aspect! Shop for the Grow Light Used by Interior Designers, Growers & People Like You! | | | | | 05-05-2009, 10:35 PM | #5 | | Senior Member Join Date: Nov 2006 Location: Orange County, NY Posts: 1,067 |
Don't quote me on this but I have been told that civilian market GPS units are incorrect by some meters on purpose compared to the military/govenrment units. __________________ 
McLaren F1 - BMW M Power S70/2 | | | | | 05-05-2009, 11:12 PM | #6 | | Senior Member Join Date: Feb 2009 Location: usa Posts: 378 |
hmm, i dont know anything about this but i would think that the vehicle speedometer is more accurate then gps through satellites. | | | | | 05-05-2009, 11:25 PM | #7 | | Senior Member Join Date: Jun 2003 Location: Greenville, SC Posts: 9,356 |
Quote: Originally Posted by Ji Money Don't quote me on this but I have been told that civilian market GPS units are incorrect by some meters on purpose compared to the military/govenrment units. | That was true years ago. They are pretty accurate now. Quote: Originally Posted by performanceisland hmm, i dont know anything about this but i would think that the vehicle speedometer is more accurate then gps through satellites. | You need to be going straight to get a good reading. __________________ ...steven
BMW CCA #146825
1996 BMW 328ti • 2003 MINI Cooper S • 2016 M235i
www.bmwcca.org
| | | | | 05-05-2009, 11:32 PM | #8 | | Senior Member Join Date: May 2006 Location: Memphis, Tn Posts: 1,299 |
Quote: Originally Posted by spidertri Same. The manufacturer wants it to read higher rather than lower. If it read lower then people could sue the manufacturer for speeding tickets.
Every time I have driven by one of those police trailers that tell you your speed it has been slower than what my speedo read. | +1 __________________
custom dual exhaust,M3 front and rear bumper, 10.4 inch roof mount drop screen, Viper alarm system, DSII's rims, M3 Vader Seats, M3 Mirrors, Carbon Fiber CAI, Smoked Corners, Side Markers, Leatherz armrests, black grilles
225k miles and still the Ti goes on | | | | | 05-05-2009, 11:59 PM | #9 | | Z3 Join Date: Jun 2003 Location: Usa Posts: 660 |
A good test is to drive @ 60MPH for 1 minute just after resetting the OBC to read AVG MPH.... They will not match ________ 2008 Cup
Last edited by Bozola; 01-31-2011 at 03:42 PM. | | | | | 05-06-2009, 11:56 AM | #10 | | Member Join Date: Feb 2008 Location: Ontario, Canada Posts: 67 |
Thx folks, phew, i thought i was the only one. I will place that issue as "common". | | | | | 05-06-2009, 03:58 PM | #11 | | Senior Member Join Date: Aug 2005 Location: Florida Posts: 2,525 |
Changing tire sizes from stock sizes will also affect your speedo.. I would say something seems out of whack because you are running a taller tire, and your speedometer is reading high, it should actually read a little bit low. | | | | |
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