[NjPrince]

Hey guys I was wondering if anyone has ever had this problem before and if you have an estimate on how much it would cost to fix. I have received a 2006 bmw 330i as a gift from my parents and it has hit 110k miles recently and I haven't checked how many MPG I was getting so I decided to check last week when I filled it up completely. From a full tank I only received 205 miles. Now when you do the calculation that comes out to be a whopping 12.8 mpg when I payed $63.25 for a fill up. I've been driving slow and safe the whole week and its been all city.

Does anyone know what the problem might be? I was thinking it might be my oxygen sensors. Please let me know before I have to go see a mechanic..thank you very much!

[3me]

If you are driving conservatively, then there is def something wrong. I have a 325i and, unless I haul ass, I have problems getting down to 12 mpg. I have a bad feeling it might be expensive to fix though. It would be easy to tell if you were running rich though.

[dmorga1]

A visit to a competent BMW independent shop would definitely be in order. Do NOT take this car to just any mechanic, because if they don't have the right tools to read codes, they'll just be guessing and start replacing stuff.

Do you have any warning lights on? Service Engine Soon?

12.8 is definitely very low.

[3me]

oh ya i should have mentioned it. pretty much never take it to anyone besides a very trustworthy independent shop that specializes in BMW. Do not just go to anybody. Good luck hope I am wrong and that its an easy fix. Would like to see the diagnosis.

[fdriller9]

When's the last time the car was in for maintenance?

Get a bottle of fuel injector cleaner and pour it into a 1/2 tank.
New Spark Plugs
Check if the air filter is dirty. If so, replace.
And check your tire pressures.

[3me]

dude...I am not a mechanic. But if you were to have everything cleaned, new filters, new oil, and air, there would only be like a 4 or 5 mpg MAX if you drove the same way. slooow cautious city driving should get you in the 20's easily. I think he has a snook in his snizz

[Brentster]

A buddy of mine was getting crappy mileage in his 08 so he cleaned his mass airflow sensor. Took him just a few minutes and he gained 5 mpg.

[fdriller9]

Originally Posted by 3me

dude...I am not a mechanic. But if you were to have everything cleaned, new filters, new oil, and air, there would only be like a 4 or 5 mpg MAX if you drove the same way. slooow cautious city driving should get you in the 20's easily. I think he has a snook in his snizz

Yea but bumping him up 4 or 5 mpg will be just under what the car is rated for city driving.

I'm only getting 15mpg. That's because I drive in the city 24/7 with an occasional 100 mile trip home every couple weeks. After that 100 mile trip, it only really goes up to about 18-20mpg. 20 if I'm really babying the throttle.

Originally Posted by Brentster

A buddy of mine was getting crappy mileage in his 08 so he cleaned his mass airflow sensor. Took him just a few minutes and he gained 5 mpg.

Yea another good point to look at.

[dcat151]

I don't know if the MAF sensor is the problem here, but I agree that it's a good idea to keep it clean. I clean mine every time I change the air intake filter.

[3me]

Originally Posted by *********

Yea but bumping him up 4 or 5 mpg will be just under what the car is rated for city driving.

Ya but that is worst case scenario. I doubt that much stuff can be messed up for him. But who knows. If that is the case then his car is seriously being suffocated.

[VTECaddict]

"city driving" has a lot of variability. i get ~15-17mpg when i'm home in the bay area and ~13-15 down here in socal.

[NjPrince]

Thanks guys Im going to get it checked out today, ill post to let everyone know what the problems were.

[simexous]

I know I am reviving an old thread here, but would be great to know the result of your diagnosis. I am in the same situation. It seems that whatever I do, I can't get more than 12-13mpg in the city, and this is with very conservative driving..

I changed the plugs, all filters (gas, air, oil). and it's not throwing any codes.

mine is a 2005 330i with ~ 100Kms and 19" rims (not OEM). Wondering if I should just switch back to 17 ?!

Thanks,

[GoRomeo]

yeah something is wrong cuz I get about 25MPG avg. here in California. See if you can pull service recods. I would start with the basics by replacing spark plugs, air filter, coils, clean MAF sensor, and add a techron fuel system cleaner.

I have done all these services except for coils....oh also did a Charcoal delete...

[simexous]

Yeah city driving here in Casablanca is pretty much like drive for 50 meters or less then stop at a light... and in between slow down for speed bumps and/or potholes...

but even then, I am told I should be getting no less than 16/17mpg w/ my driving style. Took it to the Dealer today, computer diagnostic doesn't throw any codes. They said they kept it for more checks since I also told them about noticeable power loss when AC is on.. let's see what they'll find. Just wanted to get other ideas in the mean time, besides the usual suspects (plugs and filters) as those have been recently changed.

Thanks

[300e]

I get 23 without thought tank after tank in my '06. I've got 74k for comparisons sake and my daily commute is 17 miles on secondary roads. Occasional spirited driving included.

If I get a few extended highway trips its closer to 25. Time for a check up. Report back and good luck

[simexous]

Just called the dealership and they said they found that the radiator needed replacement. I occasionally need to top off the coolant. Also after 30 minutes to an hour of driving, the cabin gets pretty hot especially at the legs level.. power loss is very noticeable when AC is on as well. They said all of these symptoms are related. Might also explain bad fuel economy in the city.

They still have the car for now. we'll see what happens after they replace the radiator (~ $700 job )..

[tcharged]

I average 26-29mpg with mixed city and highway driving. Clean your MAF, replace air intake, change spark plugs, check tire PSI. All of those give me great mpg on my 06 330i.

[tigermack]

I drive pretty much 75% city and get around 21.5-22mpg without trying to conserve gas... something definitely wrong at 12.8 even when you're driving quite aggressively...

[simexous]

Yeah definitely something wrong.

In my case, it seems idling is what eats up most of the gas. BMW could not detect anything... they relied on the diagnostic only..so I wasn't surprised.

I will try cleaning the MAF next and add some Techron...