My trick is take the city mileage announced and take it as your combined real mileage reference. You should be on target.
My x1 28i xdrive is giving me around 12.5 l/100 km (18.8 MPG) city and 8 l /100 km (29.4 MPG) on the higway. I have noticed that the car is very sensitive to any kind of elevation on the road.
If the road is flat your mileage will go under 8 l/100 km easily ( more than 29 MPG) but add a couple of hills and you will see a big drop of performance.
In Canada, the "test" resulting of the "official" rating for fuel consumption is made on a treadmill so the weight factor isn't an issue at all. The real life is very different.
This summer I wen't to Ocean View Nj and was driving essentially on the road " 9 " which don't have many red lights or stop signs so your speed is very consistent at around 35 miles an hour. The fuel economy on this kind of road is amazing on the X1. I was getting around 7 l / 100 km (33.6 MPG ) !!! Remember this is an all wheel drive unit !
Where i'm living I'm going through traffic lights and stop signs at every thousands feet. The result ? I can't get better than 12 litres / 100 km in a week ie 19.6 MPG. Every time you put your foot on the throttle to GO from 0 to anything the car is using a lot of fuel. In fact the realtime consumption needle is always at the top at more than 20 l/ 100 km ( 11.7 MPG) each time I'm accelerating.
The "official" numbers will never be realistic till they test it the way we have to drive it.
Last edited by loukas135; 10-03-2012 at 12:20 PM.