Help... Only 10 mpg

[SilverSlug]

So the onboard MPG calculator says 14.6, but I've been tracking it manually using an iPhone app, and I get an average of 10.1 MPG.

Anyone else tracking manually?

[Scharbag]

Originally Posted by SilverSlug

So the onboard MPG calculator says 14.6, but I've been tracking it manually using an iPhone app, and I get an average of 10.1 MPG.

Anyone else tracking manually?

I track mileage with Fuely. I range between 17L/100KM (14USMPG) to 22L/100KM (10.5USMPG) when tracking with Fuely. Most of my driving is in the city and a lot of it is on fun twisty roads and I am usually in second gear at higher RPM.

Reset you MPG stats in the car and try another few tanks and see if you are still way out. I did have issues with failing front O2 sensors that had not set codes but dragged my mileage down quite a bit.

Cheers,

[SilverSlug]

Hmm interesting, so you are getting 10 MPG too, and you expect it that way?

I track MPG using Mileage Keeper and Fuely too. My concern is that the onboard MPG calculator is very inaccurate. I just reset it, so we’ll see how it turns out over the next few tanks compared to the tracker apps.

Did you have any OBD codes for the O2 sensor?

Have you ever replaced your fuel breather valve?

[akkando]

I did some quick math at the pump and it looks like I'm averaging 12 mpg overall. Bought new front O2 sensors and hope to have them on by next week. Hopefully solved some of my MPG issues.

I've read that thermostat can contribute to bad mpg as well.

[RedScytheM3]

Originally Posted by SilverSlug

So the onboard MPG calculator says 14.6, but I've been tracking it manually using an iPhone app, and I get an average of 10.1 MPG.

Anyone else tracking manually?

What are your driving habits? What settings do you drive with? How old are your injectors and spark plugs? How old is your air filter? What kind of oil are you running? Tire psi? A lot of factors go into mpg, but depending on how you drive and shift will account for a lot of your inefficiency issues. I tracked my mpg with the onboard computer and regularly got 14 mpg by driving the car normally, keeping it under 3 krpm, doing occasional take offs to redline, and mostly driving in the city. I only ever got above 17 mpg when I'm on the freeway going 80 mph+.

[OmairK]

I get about 190 miles at the quarter tank mark. I never let the light come on. This is the biggest gas guzzler that I own.

[Bpark1977]

Using the onboard i average between 14 and 15mpg. I put it in M mode once it's warmed up, do mostly city driving with the occasional 2 mile freeway section, and am running test pipes with an Eventuri so I'm a little rich on the mixture. 10 seems a little on the low side, but not unheard of. As others have stated, this is the "most thirsty" car I've owned. Oh yeah, I'm 6mt as well in a vert (bad aero).

[amrazM]

bruh u cant be serious that youre concerned about fuel consumption

[Scharbag]

Originally Posted by amrazM

bruh u cant be serious that youre concerned about fuel consumption

^^^This

Just be thankful you don't own an S85. My buddy uses between 25 and 30 L/100KM in his M5... He drives with ghusto, but still...

It is all about the smiles-per-gallon!!

[PAM3Guy]

Using calculation method, I typically get about 11-13 mpg with mostly city/suburban stop light driving, generally under 3.5K rpm as well, and only in M Mode occasionally. At about 67K miles now, air filter is clean/new, spark plugs and thermostat are new since early 2019, O2 sensors and injectors are original AFAIK, and coils are original except one, per prior records. Bank 2 TA replaced in Oct 2017, just replaced bank 1 TA a week ago and the fuel breather valve as preventative maintenance, though no indication the fuel breather wasn't working.
I wonder if I should replace O2 sensors anyway?

[SilverSlug]

I shouldn’t be concerned about fuel consumption? Really?

Excessive fuel consumption could be an indicator of a mechanical issue/problem, or maintenance item that needs to get sorted out.

I’m not crying about fuel cost, I just think it’s better to have a fully working, well oiled machine. Gtoh if you don’t like that or prefer to run your M into the ground.

[mapster37]

hopefully you did not buy your car for fuel mileage...

[cowabungadude]

I average 17mpg (manually logged in Fuelly) but it's probably more highway miles. I also think I'm pretty light on the throttle unless I'm in the canyons or something.

[SilverSlug]

Originally Posted by mapster37

hopefully you did not buy your car for fuel mileage...

GTFOH... Go drive your beater. This thread is for men who operate their machines with top notch efficiency.

[SilverSlug]

Originally Posted by cowabungadude

I average 17mpg (manually logged in Fuelly) but it's probably more highway miles. I also think I'm pretty light on the throttle unless I'm in the canyons or something.

Indeed, highway miles will help a lot. I do a considerable amount of highway driving as well, and have never seen mpg above 10.5.

I had a CEL pop up for High Emissions twice, but went away after I restarted the car, and hasn't come back since, but I can't help to think that maybe this has something to do with my mpg being below 10 mpg.

[SilverSlug]

Originally Posted by PACarGuy

Using calculation method, I typically get about 11-13 mpg with mostly city/suburban stop light driving, generally under 3.5K rpm as well, and only in M Mode occasionally. At about 67K miles now, air filter is clean/new, spark plugs and thermostat are new since early 2019, O2 sensors and injectors are original AFAIK, and coils are original except one, per prior records. Bank 2 TA replaced in Oct 2017, just replaced bank 1 TA a week ago and the fuel breather valve as preventative maintenance, though no indication the fuel breather wasn't working.
I wonder if I should replace O2 sensors anyway?

Fuel injectors and coil packs don't have to be replaced unless they fail, which I understand is the same for O2 sensors (since they would throw up a CEL code if they failed).

However, I wonder if there is a threshold where these components work well enough to to avoid getting a CEL code, yet struggling to perform as they should.

That being said, you should definitely drive your car the way it was meant to be driven (way above 3.5k RPM). The higher revs will keep the injectors clean and burn out carbon build up.

[PAM3Guy]

Originally Posted by SilverSlug

Fuel injectors and coil packs don't have to be replaced unless they fail, which I understand is the same for O2 sensors (since they would throw up a CEL code if they failed).

However, I wonder if there is a threshold where these components work well enough to to avoid getting a CEL code, yet struggling to perform as they should.

That being said, you should definitely drive your car the way it was meant to be driven (way above 3.5k RPM). The higher revs will keep the injectors clean and burn out carbon build up.

Yeah, that's been my experience with injectors and coils as well, though I've had O2 sensors get lazy on a prior car (not a BMW though) without throwing codes so hard to say for sure. I imagine the other engine sensors for this car are more sophisticated and so would probably throw a code if something was off, but I too wonder about that threshold.

And I am aware that revving the car keeps things cleaned out ("Italian tune up") and I do try to rev it out when I can, but around here in the burbs, doing that on many roads will quickly get you in license purgatory. Lots of patrol cars around. That said, when I replaced my TA 2 weeks ago, I opened the throttle butterflies and looked down into the valves and they looked extremely clean. Obviously couldn't see all of them, but hopefully that meant that things are in fairly good shape.

[akkando]

sadly I won't be installing new o2 sensor today to check to see if this helps my gas milage because FCP euro sent me one correct sensor and one for a Volvo.

[tlrid3r]

Depending the mileage there is a few items to do. This is what I did @ 120k miles.
All 4 o2 sensor (bosch)
Injector refresh @ : https://injectorrepair.com/contact-us/
New plugs (ngk)

Was unable to replace coils due to national back order.

I was averaging 14mpg on the dash and it jumped to 20mpg.

Car also felt smoother.

I mostly track my car so mpg is not my concern but, as mentioned here it's a good indicator of something needing attention.
mostly noticed the improvements driving to and from track, plus city miles. So a lot of freeway miles.

[tlrid3r]

Also if anyone know how to source ignition coils with out being the $300 ea. oem branded Bosch, let me know.

[PYE46M3]

Originally Posted by amrazM

bruh u cant be serious that youre concerned about fuel consumption

Go live in San Francisco where 91 octane is $4-$5. We will see if you care about fuel consumption when you pay $300-$400 a month in gasoline!

[Scharbag]

Originally Posted by PYE46M3

Go live in San Francisco where 91 octane is $4-$5. We will see if you care about fuel consumption when you pay $300-$400 a month in gasoline!

Suggest you buy a Prius 😝