I get around 16-18 in the city but I drive like Mrs Daisy is in the back. On the "motorway", I avg around 21-22...

When I first bought my X3 (2.5), I took it on a 2K mile run. I noticed that my optimum mpg was in the 70-75 range. Once I locked it in at 80 or better, I actually saw it start to diminish (this was both computer calculated and actual mpg based on full tank mileage calculation). I never actually tried a steady lower speed (55-65) so it might be in there somewhere, but who has that kind of patience? Anyways, at around 80+, I think the drag starts kicking in and actually worsens the mpg - but that's just a guess. I've got a friend with a 3.0, perhaps we'll have to try an X3 x-periment . . .

About 2,500 KM on my 3.0 X3 so far.

Over all so far 13.3 liters / 100KM seems to be my avg per the onboard computer works out to 20.9 cdn MPG ( 17.4 US MPG) Mostly city/commute to work ( 24KM /15 mile round trip ) speeds range from 100KM ( 62 MPH) hwy section to 30 KM ( 20mph ) school zone.
My daily driving is big mix of stoplights, residential and short highway sections of driving, so pretty much worst possible for good mileage.

I had one 120 mile/ 200KM round trip highway, I hit about 26-27 MPG cdn ( 22+ US MPG) Avg speed about 120Kph/75 mph with lots of high speed passing.

Also FWIW the onboard computer is almost dead on compared to calculating milage after each fill, which I'm going to continue to do until engine is broken in

My wifes' X3 2.5 averages 17mpg in town and 24-26 highway. This is relatively constant over one year of ownership. The other interesting part is we are running this car on regular gas . A friend of mine is an engineer for a petroleum company & has researched this and on newer cars there seems to be no problem using regular & no noticable decrease in power.

USA Today on line has an article regarding this entitled "Why use premium gas when regular will do?"

My X3 2.5 averages 21 mpg. I do half highway / half non-highway

--Larry

question on effect of overfilling gas tank on mpg calculation
 

...was wondering, when I fill the gas tank I top off to the very top (what the signs at the gas stations say not to do). This 'extra' gas is not noted in the computer generation of the mpg number as it is probably above the volume indicator - right?
So resetting the mfg consumption calculator after filling the tank will give an inaccurate number, i.e. better than reality - am I right?...or am I huffing too many gas fumes.

I had a 95' 325i that would knock and ping on regular gas, and my 04' 325xi seems to do well but just not have the get up and go that it should. Now my 03' Pathfinder runs fine on what ever I put in the tank. Wonder how the 06' X3 will do?

Fuel mpg
 

Just returned from 4000 mile trip in my X3, manual trans. These are measured gas consumption not readouts from obc:
55-60 mph -----26.1 mpg
60-65 -----25.6
65-70 -----25.2
75-80 (A-C on)--23.2
Best mileage achieved was 30.8 for 200 miles with a 30 knot tailwind!

Overall mileage for the whole trip was 23.8. This included local driving and gravel road stuff.
Overall mileage since purchase (6250 miles) 22.8. I live in a rural area and keep the revs low with a light foot.