The X5 is heavy what impacts MPG more than anything is stop and go driving.

I normally take my foot off the gas when the light turns red and roll in to the stop.

Yes if drive above 70 the wind resistance is a factor but the fun factor is to big to make that compromise.

If you take it easy around town/in stop and go traffic you will get better MPG and still can have fun on the highway.

Shifting "manually" at 1500 rpms (yes, boring, I know) yielded me 19 mpg in the city and 22 mpg on the highway.

I'm now getting a combined 19.1MPG over the last month. I'm not taking it ultra easy feathering the gas but not hammering it every chance I get either. Shifting manually helps or at least leaving it in sport mode. Holding the gears longer helps = less shifting.

I would like you to test that :

- Go into the car, put the key (not start the engine).
- Reset "Travel computer" and "On board computer" (so, all data are erased).
- Now start engine, for few minutes (10 or 15 minutes), but don't move the car.
- And now, you can go for a ride.

You'll see MPG is not the same on the "TC" and the "ODB" !
I think it's strange, because they were "0.00" before moving the BMW.

I'm not sure. If someone can try this method.

It's hard for me to say what i want !!! i hope you understand me !

Just got back from my 1600 mile road trip which took me over a flat stretch of central California across the Sierras and the coastal ranges on the way back. I averaged 19.2mpg which was a tad bit disappointing but explainable because I did a lot of driving on the clogged freeways and inner streets of LA. I did get almost 22mpg, average on the way out on the open freeways which was impressive.

Overall, I would love to get the diesel both for the power and mileage specially in the light of the lower diesel prices of late, but someone I know just payed 10Gs more for a slightly less optioned Xdrive 35d, which I find difficult to justify.

The best way t get good mpg is to simply use the technique a driver's ed instructor told me many decades ago -- just drive as if there was an egg between your foot and the throttle.

Now, I am not advocating this method, as it takes away all the fun of driving... but if you want the absolute best mpg, that's how you do it.

Cruise control does not work the best in non-level situations, as a constant speed is not the way to get the best mpg in hilly country. Cruise applies too much throttle on the upwards part of hills or rises to maintain a constant speed "no matter what," even downshifting to keep the speed up. The best mpg in hilly country is to slight let off the throttle on the upwards bit (avoiding downshifts to the extent possible), slowing 10-15 mph by the time you reach the top, and gently picking-up extra speed with a little extra throttle on the downwards slopes to "get a run" on the next hill.

Again, I am not proposing this, as (a) it's not much fun (b) the changes in speed irritate other drivers, and (c) police like to nail people on the bottom of hills where you'd have the extra speed... but that is the method which provides maximum mpg.

I have a 2008 3.0si that was quite loaded with a lot of boxes since I was driving from Dallas to Denver.

I started off with 93 Octane from Chevron in Dallas and according to the computer averaged 21 mpg.

As I filled up in Amarillo with only 90 octane, I noticed that the MPG shot up to around 23 mpg.

My last fill up was in Trinidad, Colorado with 91 octane at a Diamond Shamrock or something like that and here's what I finished with.

http://img197.imageshack.us/img197/2574/mpg.jpg

Now, the minimum speed I drove was 65 and the max was around 85 mph. I was wondering if the computer was just being generous or if the gas is different in the mountains? Does higher altitude affect mpg?

Just wondering b/c I was quite surprised with the mpg.

I assume that mpg is better at higher altitudes where the air is thinner. Thinner air = less air mass = the computer send less fuel = your HP sucks, but you get great gas mileage...

MPG
 

I regularly drive upstate on the weekends from NY (2008 3.0) and almost always average between 24 and 27 mpg. I think that's pretty great considering I'm coming from a Honda Ridgeline where I was barely making 20. Oh, and I also tow a 4000 lb Airstream a few times a year and get 14-15 mpg. Yes, the torque is not neck breaking but it all works for me. I love this car.

James

I agree that maximum power is reduced at altitude due to less oxygen. In practice, the driver is likely to just push down on the throttle more to compensate, so I don't see why this alone would change fuel consumption. If anything, I would think that the fuel map would be less optimized, and fuel consumption would therefore increase at altitude. A quick search on the web for a source suggested that EGR mapping will be off as well, thus reducing efficiency.

I used to drive an Expedition with a 4.6 litre V8 from sea level to 15,000 feet and back to visit a customer, and it was a dog beyond 12,000 feet, even unloaded. Mileage was reduced, likely because it couldn't pull the usual gears.

I would put the observed mileage variables down to driving practices, roads, tailwinds, stop/start cycles vs steady cruise, and so on. Also, who says that the fuel purchased is really what it says on the pump? The pump label is a minimum, not an actual. Then there are the variable effects of ethanol %, ambient temperature changes, and ambient humidity changes.

All that said, the best fuel economy I ever got on my X5 3.0 was on 89 octane, measured over a full tank and not on the OBD.