When cruising at any speed .... steady, exactly on the mark. If I push the recalculate button on the trip computer's avg. speed reading, it always comes up 4 or 5 mph slower than the speedometer. I have the nav kit so my OD is quite small compared to standard. But it I can't be misreading 5 mph. Of course this wouldn't make much diff except if the computer is right, and I am going 5 mph slower than the OD says, then that means my warranty will expire earlier that it should.

How can there be a difference anyway? Where is the trip computer getting it's speed info from? And it makes no difference what speed ... 60, 70, 90, 110. It's always 4-5mph off.

 

It's not unusual for the speedometer to be reading 3-5 mph higher than the computer...it's within the tolerance for the speedometer +/-5% but, never below the actual speed, so you can wind up with a +10% variance.

 

BMW and most European manufacturers are notorious for "high" reading speedometers. This is due in part as a safety measure (to keep us from getting too many tickets?) and may even be proscribed by some wacky EU legislation making it necessary to calibrate the speedo on the high side.

 

The computer is correct. Not the big dial.


By the way, I've convinced my girlfriend that they dial that she sees is off by 15-20mph! That way I can drive 90mph without getting yelled at!
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MCS, with some stuff. Stuff. Just stuff, alright!

 

The speedo seems to read high...but the odo always seems to be spot on in it's accuracy..

 

My Garmin StreetPilot III Nav system gives me a GPS calculated speed. My speedometer reads high by about 5mph at interstate cruising speeds. I have never bothered to use the trip computer's average speed display other than to reset it.

 

>>My Garmin StreetPilot III Nav system gives me a GPS calculated speed. My speedometer reads high by about 5mph at interstate cruising speeds. I have never bothered to use the trip computer's average speed display other than to reset it.

Yucca--

I also have a Streetpilot. PM me with where/how you mounted it, if you wouldn't mind.

Thanks,