Has anyone checked the accuracy of their '06 530i speedometer? I have a Garmin StreetPilot i-series portable GPS device and when in driving mode, it displays your current speed. The Garmin unit shows that the speedometer on the 530i is approximately 3 mph too high. I thought that the Garmin was to blame for many reasons until I moved it to our '06 Pilot. In the Pilot, the Garmin speed indicator matches the Pilot's speedometer.
Anyone else experience the same type of results?
On another speed related note, on the pror BMW 5-series software version, when I would engage the cruise control, the little white speed indicator would never match what the digital readout displays right at the time you set it. Once I upgraded my software, the white speed indicator matches the digital readout exactly.
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| Reply » Speedometer Accuracy |
Speedos are about 3 MPH too high in general on BMW's.
This accomodates for wheel sizes up to 22".
They always take the conservative side, it is better to be going a little slower than you think, rather than faster.
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| Reply » Speedometer Accuracy |
I have found the speedometer in my 2003 325Ci to be very accurate: even at well-above-legal speeds, it reads just 1 mph high.
Keep in mind that you need to perform these tests on a level road: GPS does not have very good vertical accuracy.
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| Reply » Speedometer Accuracy |
Your rationale about the 22" wheels is incorrect. BMW assumes does not make allowances for out of spec wheels.
Quote: Speedos are about 3 MPH too high in general on BMW's.
This accomodates for up the wheel sizes up to 22".
They always take the conservative side, it is better to be going a little slower than you think, rather than faster. |
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| Reply » Speedometer Accuracy |
Quote: | Your rationale about the 22" wheels is incorrect. BMW assumes does not make allowances for out of spec wheels. | I did not mean BMW themelves accomodates. Just that larger wheels lowers the delta of the speedo inaccuracy.
In other words, if you add larger wheels the speedo will get more in line. Not by much however.
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| Reply » Speedometer Accuracy |
Quote: Just that larger wheels lowers the delta of the speedo inaccuracy.
In other words, if you add larger wheels the speedo will get more in line. | That isn't the rationale, as it is intended that whenever you move to a larger or smaller wheel, you select a tire size with the same rolling diameter.
Speedometer accuracy is regulated, and the manufacturers are permitted to read high, but not low. A typical regulation is +5%/-0%. It differs between various jurisdictions, ie EU vs USA, but the approach is consistent. To accomodate manufacturing tolerances, the manufacturers always design for the speedometer to read several km/hr high, so they are never offside. It isn't anything new, and it isn't specific to BMW. BMW typically read a few km/hr higher than some others, but it is easy to adjust for it yourself if you run a measured mile (or use a GPS) and figure out what your typical variation is at usual highway speeds.
Lots of info on the web, by searching forums or otherwise.
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Speedometer Accuracy