I wouldn't do that if I were you. You're speedo might be right but your total mileage will be off. Better have the dealer make the correction which have heard is possible.
I was talking with my dad in EU the other day and apparently it's more or less a European thing. We don't know for sure but we guess safety agencies or car makers are doing this to entice people to drive within the speed limit which they've been cracking down quite a bit over the last decade. Apparently they are all doing it over there.
Why don't they change that for the US market is a mystery. Perhaps BMW MINI thinks it can't hurt. But the point is that the total mileage is not affected. If you change your tire size not only it will show fewer miles but you might also get a small hit on MPGs as it will be harder on acceleration.
just something to consider.

It's not terrible though...

 

Re-read my post as you missed the part the mileage is off 30 miles per tank and speed is off already. They are not going to re-adjust the mileage on the odometer and computer to correct what should be the mileage. Local dealer took 3 tries before they could get a mud flap installed correctly. Am I going to turn them loose on reprogramming the ECU? HFN.

I also call BS on EU manufacturers setting the speedo to show faster than what the car is driving. I work all over the world and have rented cars on 6 continents and I spend a lot of time in Europe. I have rented almost everything possible in the German market including a few exotics - they all have accurate speedos, including the Mini's. The one thing that does bother me is the 265 KPH speed limiter that most high end cars have on them. Having a 6-speed Jag XJS pulling hard in 4th with it shifting into 5th at 260 KPH and having it set you back in the seat again on acceleration and hitting the 265 limiter and because of that hard acceleration coasting up to 273 KPH is quite a letdown. Driving on a "no restrictions" part of the Autobahn does have its advantages such as no speed limit.

 

Sorry but I didn't read every post on this thread.

Perhaps, yet my dad confirmed that on all of his two newer cars which do that. One is a Ford and the other is a Hunday. But maybe they're all glitches... or his GPS isn't working properly. We have no official information. just what he noticed which matches approximately the amount of error. Speedo error might just be more common than I thought.

As far as I have monitored my total mileage on the MINI is accurate... just the speedo as the 3mph error.

 

So, how's the mileage?

 

deleted this latest post... miss looked at the date of the post I was responding :p (I didn't noticed I was not logged in at first)

 

"It is more accurate at slower speeds but the computer mpg vs. actual is plus or minus 3 mpg for every tank."

Your observations make sense and at now close to 3K, I have a pretty good picture of what I have to expect for the future.

City driving is now about 26 MPG from the computer and what should really be around 23. As for me, it is an improvement from the original 18MPG and my calculation were right at the time.

As for highway driving at high speed from a recent trip, I managed mostly 32MPG from the computer, so maybe about 29 should be close.

This should make sense in the way the sport button is always on and the engine mostly all the time in the 3.5K-5K RPM range for best torque and response.

But, according to the MINI claim about 26/32MPG, it is pretty much what I can expect from my driving style since the car's break in from new.

 

My mileage is similar to yours, 25-26 in town and 31-32 highway, about what I expected. My computer is consistently only 1 mpg higher than my calculation. On my 2007 MCS the computer was right on the money.

 

So, what is the odometer on your car now?

Do you run on 91 or 93?