It only counts the time the engine is running. If you drive in a lot of stop/go, that is probably a correct mph reading. I have a commute of 50 miles/1way 90% highway with 4 stop lights and almost zero traffic. My average is ~40mph. Any time spent idling and not moving, rapidly drops your average.

 

...and watch your instantaneous mileage drop to single digits when you accelerate from 'not moving' to road speed. And don't forget, those single digits factor in to the double digit average.

 

My display always shows around 2mpg more than actual calculated MPG.

 

Well, since I reset it, my average speed has been a bit over 35 mph. I'm still seeing about 21 mpg when I fill up, and the OBC still says 24+ mpg.

Interestingly, both my actual mpg and the OBCs calculation of my mpg are staying consistent.

 

So far testimony has been the major contribution to this thread as opposed to advice. Time for some advice: Put the pencils and computers away and enjoy motoring in one of the worlds most entertaining motors. I don't remember BMW/MINI promoting their products as 'economy'.

 

you can re-calibrate it from the "secret obd menu". just search google r53 (or 56 it's not same with r56 but pretty close, i have r56, but i read it from r53 forum) secret obd menu, reaching it is kinda tricky. after reaching it; it has to be under 20th submenu. calibration number has to be preset 1000. if you're burning let's say 10 percent more than that, you have to reset it 1100. it's kinda tricky to change the number, you go into the submenu 20.1 and wait for hundredths to set, then same for 20.2, it's for tents etc. etc.

 

It has been interesting to read all these responses about how the computer overestimates the mpg.

While I agree that the enjoyment of driving my MCS far outweighs any concern over minimal mileage differences, I appreciate knowing what mpg other drivers are getting so I can gauge whether my Mini is in decent health.

Since my last post, I have continued to average about 40 mph and get about 21 mpg. The computer continues to estimate 24 mpg. Others have reported similar numbers, so I'm less worried about my car now.