06 Crappy Gas Mileage

Owned my 06 X3 for 8 months now...it just hit 60,000 miles. For the first few months, the gas cap light would illuminate each time I filled up. After a few starts per tank, the light would go off. I have filled it with premium BP fuel each time I have filled up. Now I haven't seen the light in a few months but have noticed that I get terrible gas mileage...14 mpg. I don't know if the previous 2 owners used premium fuel or not. The car seems to run fine and has great pick up when I accelerate. Would a dirty fuel filter cause any problems other than impacting mpg? Does this sound like it could be something other than the fuel system?

Hey bud, we live about in the same area but I am in the suburbs and around here with about 70% city and 30% highway i get about 18mpg average. You in the city (depending on how you drive should be getting about 15-16). When you accelarate in Drive what does the car shift at?

My wife gets 18mpg with half city/highway with a N52 motor in Chicago. She's light on the gas pedal. It really depends on your driving habits and traffic. Have you recently reset the MPG meter after purchase?

I used to get around 12. Installed new intake boot and plugs and now am getting 14.7 for in town driving mostly now, WHOOOOHOOOOO!! This is using Chevron regular. Premium made no difference in mpg in my case anyway.

One of the very few problems with the 5 speed auto box was a tendency to hold in gear longer than normal -- so you were burning more gas. I notice this sometimes when the car is cold but a "blip" with the gas pedal usually shifts it up. I think there might have been a bulletin about this early on. I generally get between 14-16 in town and 20-22 on the road in my '06 with 94K miles. I have had the intake boot/mas (cracked) replaced and I did notice an increase in performance, but not gas mileage.

With the 2.5i, getting 24 mpg (U.S.) or 29 mpg (Imp.) or 9.7L/100km with mixed hwy. (< 55 mph) and light in-town usage. Chevron 91 or 93, or Shell 91 no ethanol.

If I was only getting 14 mpg I think I would:
- look for a problem with the X3
- look at my driving technique
- look at getting a different vehicle

Originally Posted by bluskye

My wife gets 18mpg with half city/highway with a N52 motor in Chicago. She's light on the gas pedal. It really depends on your driving habits and traffic. Have you recently reset the MPG meter after purchase?

I have an 07 with the automatic and 66k and I drive relatively aggressively and use the throttle a lot. I also drive in and out of Chicago 20 miles per day and have been averaging 17.4 mpg.

My 09 with almost 113k still averages 23 with a 80/20 mix of highway and city. With mostly highway, I get 26 mpg. Picture below is from my BC today. The top number is for my commute in (about 100 miles) bottom is a six month average.

Your mileage however isn't that inconsistent with 100% city driving. What's your driving style?

As for fuel grade, I don't believe in that debate for my particular scenario. In my x3s 112k miles, less than 5,000 miles have been driven with any grade higher than 87 octane chevron. My driving style and commute derives no additional benefit to cost vs mpg/performance gain.

Quite awhile back, I started an mpg thread. Browse through it, but like I said 14 is in the bottom end of aggressive city driving. Not unheard of. I would however check all the usual suspects (tire pressure, intake boot cracks, air filter, spark plugs, ect).

http://www.bimmerfest.com/forums/sho...d.php?t=598741



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Thanks for the quick responses! I do live in the suburbs and drive short distances. I generally drive pretty conservatively around town but have been known to gun it on the highway (where I only drive once or twice a month). After reading the threads on this board, I have convinced my husband to take my X to work for his 60 mi round trip highway commute once a week to keep the new battery charged and other parts in working order. I am due for some maintenance, so in addition to fluid changes, I will have the Indy shop look at the intake boot, etc. Maybe I can edge it up to 16 mpg!!

I'm averaging about 20-21 mpg (more highway than city) and I've been pretty pleased with the fuel economy because it's still better than my Subaru. In which I'm currently averaging 17-18 mpg over the same roads. But to be fair, I do drive the Subaru much more aggressively than I do the X3.

What are your tire pressures? Are any of the brakes sticking? Did you actually calculate the fuel mileage (reset trip odometer when you fill up, drive 350 miles or so, fill it up again, and divide miles traveled by gallons used), or rely on the computer?