Not necessarily true. I initially made the same assumption. What one does with the calculation is what matters. Again checking with GPS my Odometer is very close but the speed is 5%-6% off at all times. Over 400 miles of driving my GPS and Odometer agreed within 1 mile.

 

Same here. Odometer is spot on. But speedo is off by 5%. Took it to the dealer yesterday and they confirm that all Minis and BMWs are that way

 

--->

 

I just took a 5500 mile trip in our Mini. The speedo is off by about 5-7%. The odo is off by less than 3%. I checked several times using the mileage markers on the interstate, several of these were speedometer check stations. Odo and speedometer can have differing accuracy. Anyone know how to fix this?

Regards,
Harry Faulkner

 

That is correct. I have checked the odometer every which way possible; Interstate millage markers, GPS, timed (based on speed from GPS), and the odometer is spot on. And it seems by my testing that the MPH reads high by a percentage not just a set number of MPH. (i.e. may read 32 at 30 MPH and 64 at 60 MPH). Not a big deal in my book.

 

On my Clubman S (production mid June) the speedometer reads two miles slower that GPS at all speeds between 35 and 80 MPH. I have not paid much attention below 35 mph but will check soon. This is on 16 inch wheels with a tire pressure of 35 psi.

Thanks

 

is to not change the speedo calibration unless it's 7 MPH or 10% off.... That said, those with the right tools can do it, and maybe your dealer would do it for a fee, cause it's not far enough out to justify a warranty claim...

Matt

 

This is only the case with old technology, and it's not always true even then.

Old systems - The transmission drives a cable that goes to the instrument cluster. This cable drives the odometer directly via a series of gears, and drives the speedometer needle indirectly via a spinning magnet (no mechanical coupling). You can still calibrate the odometer and speedometer separately, though. The odometer is adjusted by changing out the gears, and the speedometer is adjusted by varying the distance between the spinning magnet and the needle pickup.

New systems - The wheel-speed sensors provide a signal to the car's computer (the transmission isn't involved at all). The computer then controls the speedometer and odometer, but can apply a different "correction factor" for each gauge (The MINI gauges are computer-controlled, and have no gears/cables/etcetera - they're merely displays for the computer).

This is why the MINI odometer is usually spot-on (except for differences due to varying tire diameters), but the speedometer is often 4-6% too high. I believe that the speedometer error is intentionally-induced because of the legal liability for the automaker if the speedometer were to habitually read too low. This is likely also why the OBC-reported speed in the digital readout is closer to the truth - it's displaying the speed *before* the correction factor has been applied.

 

I just drove over 500 miles one tank of gas 13.9 gals With my gps I agree with you this is exactly what I experianced. Did not check odometer

 

Also there are laws in other countries about speedometer accuracy.

Most European countries, Japan, Australia, New Zeland, and South American countries have laws that state the accuracy can be -0% but +10% on the speedometer. So if the car is actually going 30 mph then the speedometer can read from 30 to 33 mph but can not read lower or higher than that, and if the car is doing 80 mph then it can read from 80 to 88 mph.

There are a few countries that also add in a mileage/kilometer error as well such as in Germany where the law reads -0% to +10%+2.7kph.

For all of you just a note. On a standard 17" tire there will be a change in speed of around 1.2% between a brand new tire and a fully worn tire of the same make and model. Then there ar eth differences in manufacturing of the tire brands and size chagnes and all. This can lead up to a 6% to 7% change when your replace tires on your car. I.E. when you go from OEM Dunlop runflats to Goodyear F-1 non run flats in the same size.

if any one wants more info on this subject please ask and i can expalin a lot more about tire diameters and speed.

 

These threads crack me up.

I've been on lots of other forums for other cars and motorcycles and it seems like there is always a thread on speedometer accuracy. The speedometer will always be off for the reasons shatzy62 mentions. As we say in the software industry it's not a defect, it's a feature!