Bad MPG's!!

So I purchased a 2004 525i that currently has 106k on it and the first full tank of fuel that i put in it went surprisingly fast. I was under 100 miles still when I passed that 3/4 of a tank mark. I recently sold my 2010 Nissan Titan LE V8 that got a HELL of a lot better gas mileage than that. Anybody have any suggestions? I purchased a diagnosis tool to diag my new baby. I won't be gettin it in the mail till probably the 22nd. So in the mean time, does anyone have any suggestions? Responses are greatly appreciated. Thanks!

Nothing? Really??

Before you get too worried, let a couple of tanks run through the engine. I get about 550km/tank around town on my 535xi and i don't consider it too bad. That's only about 350 miles...

Maybe its the way I drive, but I get about 450 per tank. '04 530.

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Tune up, air filter, improper tire inflation, wrong octane gas? Just an idea for things to look at.

Try to use better gas, NOT from Costco. Better brands like Exxon, Shell has less ethanol in the gas. Any time I fueled mine with Costco gas I would get a check engine light that is meaning super small vapor leak, well I test a lot times and I guess it's too much ethanol there.

Originally Posted by phlfly

Try to use better gas, NOT from Costco. Better brands like Exxon, Shell has less ethanol in the gas. Any time I fueled mine with Costco gas I would get a check engine light that is meaning super small vapor leak, well I test a lot times and I guess it's too much ethanol there.

Really? That's interesting you say that. I always thought highly of Costco, but then i can see how they would use a little more ethanol =\. I used Shell more than anything else.

What does the readout say(mpg).Bad at math but that's about 23mpg with 17 gallon tank?Im not sure on tank size.It always amazes me when I'm at the gas station and someone complains about the price of gas then moments later I watch as they heavy foot it pulling out.Not saying you just saying.

May be it's just here in Leesburg VA, we are getting gas with more ethanol (I guess they are using local suppler that sell for cheap to keep low cost gas, I don't know and can't tell this. But I know one thing at least three times I used Costco gas right next day same check engine light, but when I'm using Shell, Exxon or Sonuco I don't have this problem.

The ethanol lobby is pushing E 15, 15% ethanol. They have a few stations in the Mid West selling this, but if they can get nationwide compliance, the ethanol producers will profit.

The avg MPG read out says 15.4. I use the gas station on base and always get premium 92 octane minimum. I don't have a heavy foot, my tire pressure is golden, the tune up was supposedly done by the previous owner two months prior to me purchasing. Sorry, no I didn't ask to see the paperwork. That is why I'm taking care of this cars maintenance now as If it HASN'T been done.

I've already changed the cabin air filters, intake air filter, oil, and was about to start changing the Tranny fluid and filter until I read somewhere that its supposed to have lifetime lubrication, and changing them would be tranny suicide. Idk. I scared not to get the tranny fluid and filter changed.

Originally Posted by Frenchyrider267

The avg MPG read out says 15.4. I use the gas station on base and always get premium 92 octane minimum. I don't have a heavy foot, my tire pressure is golden, the tune up was supposedly done by the previous owner two months prior to me purchasing. Sorry, no I didn't ask to see the paperwork. That is why I'm taking care of this cars maintenance now as If it HASN'T been done.

I've already changed the cabin air filters, intake air filter, oil, and was about to start changing the Tranny fluid and filter until I read somewhere that its supposed to have lifetime lubrication, and changing them would be tranny suicide. Idk. I scared not to get the tranny fluid and filter changed.

Wouldn't hurt to get some injector cleaners, also could be fault in mass air flow sensor.

Originally Posted by phlfly

Try to use better gas, NOT from Costco. Better brands like Exxon, Shell has less ethanol in the gas. Any time I fueled mine with Costco gas I would get a check engine light that is meaning super small vapor leak, well I test a lot times and I guess it's too much ethanol there.

I've been using Sam's Club gas here in NH. Excellent so far!

27-30 mpg on 2006 530xi.

Mid 400's per tank.

Change the fluid and get them to reset the tranny adaptation.Theres a thread on here how and where in the coding to properly reset the transmission.I was corrected in that its not the holding the pedal to the floor procedure.I put 0w30 GC in mine from BMW 5w30 and my MPGs went up a little .4 or .5.Sounds like your needs to go to a good Indy shop.Research around and find who's the best in your area.

I get 11.5 l/100km (20.5 us mpg) city(ish) and 9.5 l/100km (25 us mpg) highway. These are calculated values from fill up/distance rather than what the OBC says, but the OBC is very close. No complaints at all - the 535 gets about 10% better fuel economy than did my '08 G37S and weighs more. I use 92 R+M/2 with no more than 10% ethanol. Besides, I didn't buy it to be a gas sipper...

I get 300 to the tank in my 530.

Also clean your air mass sensor.

Originally Posted by phlfly

Also clean your air mass sensor.

Where is the Mass air flow sensor located? I was told it's in the air intake "box" but theres a sensor looking componant on the hose coming from the box going to the engine. Would that be it? Because when I look up the Part online to purchase, it does NOT look the same at all....

I average about 19.4 on my e60 530i according to the computer, which to me is an incredible amount considering I have only own V8s since 2000 - one supercharged 650hp cobra with an average of 9.8mpg and my last one, a 5.7L Durango with an avg. of 12.5mpg Funny thing is every time my wife drives my car she comes back with an average of 15 mpg. I do love the idea of not wasting time to fill up all the time.

Haha! Gotta love wives. Mine is just careless. I had a 5.7 Titan LE prior, and she would just open the driver door like she had all the room in the world, when in all actuality she only has about three feet of room before the door hits a huge satelite dish next to the drive way. I've sat there and watched her do it twice. And both times I witnessed it, she poked her head out to see if I saw, then says, "oops, sorry" like that is going to take the dings right out. I swear..... And she gets offended when I tell her she is NOT driving my 525. Haha!! How DARE me right!?

I get about 17 - 20 MPG depending on traffic in 100% city driving. (Avg speeds is around 20 - 30 KMH and all the info is taken from the OBC)

2 Other things to check:

Spark plugs - have they ever been replaced? If not, I would do this ASAP. Parts should be around $40ish and if its your first time you may spend about another $40 in getting all the right tools (ratchet extensions, spark plug socket, etc.)

Engine air filter - If you clean the MAF sensor, you'll certainly come across the engine air filter also. But, I would recommend checking out the engine air filter regardless. This is another easy DIY if it turns out your filter looks really clogged. I bought an AFE pro-dry S filter (the oiled ones can cause issues with the MAF sensor) and its been great for the couple of years I've had it in.