With many of you taking delivery of a 2010 X5 35d in the coming days I thought you might like to see a graph of some real world 35d MPG since mid Aug 2009.
This graph is computed from a 'fuel log' where each time we fill up, we write down the date, mileage, gals and $. MPG is simply the miles driven since the last fill up divided by the gals. MPGLong is the miles driven since new divided by the total gals since new. The MPGLong calculated this way matches the mpg computed by the X5's Trip Computer. Note: I set the Trip Computer to zero at the time of delivery.
Using the Car Data mpg for short distances does not give you a very good feel for life time mpg. On a typical 10-50mi run the Car Data mpg will show an avg of 24-25 MPG. And we frequently see runs of 27-30 MPG. BUT our actual avg MPG from time of purchase is only a little more than 21.5 MPG. The 35d does not get very good mileage until it is warmed up. IOW the longer the run the better the mileage.
As you can see, the mpg (both per tank and since new) are getting better with each fill up

This is at least in part because of the very poor mpg on the first tankful when we were letting the engine run to keep the AC working in 100+ degree temps while adjusting the various settings, etc for each driver. The one low mpg tankful included a couple of trips to the quarry, towing back 2+ tons of sand. When towing a couple of tons, the 35d mpg drops to 15-18mpg depending on terrain.
It would be nice to compare similar mpg data from other 2009 & 2010 X5s
Funf Dreisig
Edit: the MPG in this post is Miles per
US Gallon