[type-dRew]

2009 335i xDrive automatic, 148k miles, full stock minus DCI and BMS DV chargepipe. Recent spark plugs, OEM Bosch and recent walnut blast.

So I got my car about a month ago and am slowly going through the list of maintenance and will be adding a stage 1 tune shortly.

Obviously the main goal of this car is not to get great fuel mileage, I realize that. its also an automatic and awd with 148k on the clock, really, its just not going to happen without major effort on my part. More than anything else want to see if what i'm experiencing is normal rather than bitch about it being poor.

I have a 50 mile one way commute on the highway, I hit no lights on my way to or from work and rarely get caught in stop and go traffic(once every other week maybe). I live 1 minute from the freeway on ramp with no traffic lights in between. I start my car, let it come down on idle after about 30 seconds and then leave, I rarely sit and let it warm up ever.

I do use the pedal to merge with traffic but after that i set the cruise to a gps indicated 71-73 normally, unless there is something im in a rush for and then I dont question poor mpg on that tank.

What i'm getting with basically 90% highway(i normally drive my wifes car around town unless I need to make a stop on my way back from work) is about 19.5-21mpg average(hand calculated every tank). And I actually think this is a little better than it actually is because my speedometer shows a couple mph higher than gps indicates. Which means its counting more miles that arent actually happening.

On my window sticker for the car it shows 25mpg highway and I know that new and now are totally different. But my instant read out shows 27-31mpg(consistently most of the drive) depending on headwind going down the road. Why such a massive discrepancy? O2 sensors? Fuel injectors leaking? It has index 12s.

Since all my drive is normally highway I was expecting to do a touch better than this, but obviously age and something could be wrong. So I want to hear opinions or other experiences maybe with similar commutes. It has also been stone cold since I got the car here in Michigan(0-30 degrees F normally), so that could be a factor also. No MIL or ghost codes in DME.

Heres a WOT log if it helps;

https://datazap.me/u/typedrew/log-15...og=0&data=3-21

Sorry for the book, thanks for any insight.

[320IN54]

21-23 mpg is what I get if I cruise at 70 mph while 19 mpg is what I get at around 80-90 mph. The sticker mpgs are done usually in a near perfect testing condition and throttle. It doesn't take in account slowing down in traffic or overtaking cars.

[Jeff@TopGearSolutions]

Pretty sure the read out is just a guesstimate.

That being said, usually winter blend fuels have reduced mileage, also the extra ethanol in gas now (E10) accounts for another 4% less mileage and if your car doesn't get up to full operating temps that could be another reason. Those are just on the surface of affecting gas mileage.

I've also noticed my gas mileage is worse with cruise control VS my own right foot. With your own right foot you can avoid large transient swings in throttle that cruise typically does and you can hyper mile by avoiding excess acceleration or braking. Smooth is the name of the game for MPG.

Also, have you checked tire pressure? I like to put them 2-3PSI more then recommended.

The speedo off is normal. They are off by a good 2 MPH.

Aside from doing a leakdown and compression test there really isn't much else to do to make sure the motor is good. The 02's and other stuff would normally throw a code.

I was going to suggest walnut blasting and plugs but you already did that.

I AVG about 17.5 MPG now but it's basically 100% city and enthusiastic driving. When I used to have longer commutes I would AVG 21 MPG, 19-20 spirited. These cars have a lot of torque down low and also with the turbo's demanding more fuel earlier then typical N/A cars they aren't the best for gas mileage.

[MysticRob]

Fueleconomy.gov lists your car at 17/20/25 MPG so you're just about in the middle of the combined MPG estimates, especially if you figure winter gas blends into the equation.
Ensure tires are at proper pressure as Jeff mentioned, and also take into account whether they're new or not, as tread depth will affect readings.

[type-dRew]

Originally Posted by 320IN54

21-23 mpg is what I get if I cruise at 70 mph while 19 mpg is what I get at around 80-90 mph. The sticker mpgs are done usually in a near perfect testing condition and throttle. It doesn't take in account slowing down in traffic or overtaking cars.

Yeah, and michigan in the winter is far from ideal.

Originally Posted by Jeff@TopGearSolutions

Pretty sure the read out is just a guesstimate.

That being said, usually winter blend fuels have reduced mileage, also the extra ethanol in gas now (E10) accounts for another 4% less mileage and if your car doesn't get up to full operating temps that could be another reason. Those are just on the surface of affecting gas mileage.

I've also noticed my gas mileage is worse with cruise control VS my own right foot. With your own right foot you can avoid large transient swings in throttle that cruise typically does and you can hyper mile by avoiding excess acceleration or braking. Smooth is the name of the game for MPG.

Also, have you checked tire pressure? I like to put them 2-3PSI more then recommended.

The speedo off is normal. They are off by a good 2 MPH.

Aside from doing a leakdown and compression test there really isn't much else to do to make sure the motor is good. The 02's and other stuff would normally throw a code.

I was going to suggest walnut blasting and plugs but you already did that.

I AVG about 17.5 MPG now but it's basically 100% city and enthusiastic driving. When I used to have longer commutes I would AVG 21 MPG, 19-20 spirited. These cars have a lot of torque down low and also with the turbo's demanding more fuel earlier then typical N/A cars they aren't the best for gas mileage.

Our winter mix seems to be fairly mild normally, i've never seen much variance on other cars. But it is possible this car is just affected more by it than my others.

Car is definitely up to operating temp, i see 200 on the oil temp gauge about 5 miles into the drive normally, even when its stone cold. And I go another 45 one way, on two highways without slowing down after that.

I do use cruise basically religiously, so thats a solid point. Holding the pedal myself would probably improve what i'm seeing a bit. But honestly, as long as the car isnt underperforming, im not worried about it. I just want to make sure nothing is wrong more than eke out every last drop of fuel.

Why are the speedometers wrong from the factory? Seems like most tell me the same thing. Can MHD or coding correct it? I hate reading faster than what it should, especially on stock size tires.

Tire pressures are checked weekly. They are set to what factory recommends, they are Michelin Run Flat @ 33F/38R.

I will be doing downpipes this spring, so itll get new O2s then. I wont accelerate that purchase if it doesnt seem far off from normal.

Originally Posted by MysticRob

Fueleconomy.gov lists your car at 17/20/25 MPG so you're just about in the middle of the combined MPG estimates, especially if you figure winter gas blends into the equation.
Ensure tires are at proper pressure as Jeff mentioned, and also take into account whether they're new or not, as tread depth will affect readings.

Thanks for confirming. It didnt seem 'terrible' just seemed like it could be better being mostly highway. But yeah, stone cold temps and winter fuel probably arent helping me at all.

Tire pressures are good 33F/38R, checked weekly. Michelin run flat all seasons, id say about 70% tread depth or better when I got the car. Alignment seems sound, no abnormal wears or pulling.

Thanks for chiming in guys. I'm probably just overthinking it. I like the car, I just want to make sure its performing right. Because poor mpg could mean lots of other issues in my head.

[TemjinX2]

the sticker numbers are in a temperate climate at sea level. cold weather, winter gas will all hurt your mpg.

maybe up your tire psi to 40psi..it'll help a little bit. you could possibly have leaky injectors if you havent upgraded to index 12s yet. i got 3-4mpg worst when my injectors were leaking.

[type-dRew]

Originally Posted by TemjinX2

the sticker numbers are in a temperate climate at sea level. cold weather, winter gas will all hurt your mpg.

maybe up your tire psi to 40psi..it'll help a little bit. you could possibly have leaky injectors if you havent upgraded to index 12s yet. i got 3-4mpg worst when my injectors were leaking.

The leaky injectors were a concern of mine. But it does have index 12s in it.

That said, they could be cheap Ebay 12s or something, since I havent owned it that long, i have no idea. So its entirely possible.

I'm not interested in bumping pressures up above spec, i dont need that potential 1mpg that bad, and its not worth potential funny tire wear to me. Theyre run flats and I hate them, but theyre in good shape. As long as the car is performing seemingly as it should, thats all im worried about.

[MysticRob]

Originally Posted by type-dRew

Thanks for chiming in guys. I'm probably just overthinking it. I like the car, I just want to make sure its performing right. Because poor mpg could mean lots of other issues in my head.

Something else to consider is those MPG estimates may not be dead-on accurate anyway. A few manufacturers have overstated estimates due to "miscalculations" over the years, as they don't actually drive the cars (nor does the govt) to get those numbers. My C-Max Hybrid is a perfect example with its misstated original 47/47/47 estimates. LOL

Add in the extra weight and mechanical drag of the Bimmer's AWD system and that likely detracts even more mileage from its estimates.
I know my 2008 535xi wagon, with it's massive sunroof and extra sheet-metal porkiness isn't quite getting its estimated city MPGs, and it runs like a top on Stage 1, though I stay out of it most times, as it's a 12-mile round trip city road commuter.

[Disgustipated]

Just thought I'd chime in. You really are wasting fuel efficiency etc by following OEM tire pressure settings, they aren't relevant to your tires or driving. You're AWD, it only makes sense to run 38 front and 38 rear. Get rid of those runflats ASAP, they're junk.

Next, getting a custom tune should add 2-4 mpg especially if you ask your tuner to make it more fuel efficient and to push less boost at low RPM/run it leaner on highway cruise.

Also, try using the Xdelete app from XHP. This will switch your car to RWD mode which will cause less parasitic loss, increase power by 10%~, and should give better MPG overall.

This will cost you $300-400 but will increase power (10% alone from xdelete) and efficiency.

[mweisdorfer]

Originally Posted by type-dRew

2009 335i xDrive automatic, 148k miles, full stock minus DCI and BMS DV chargepipe. Recent spark plugs, OEM Bosch and recent walnut blast.

So I got my car about a month ago and am slowly going through the list of maintenance and will be adding a stage 1 tune shortly.

Obviously the main goal of this car is not to get great fuel mileage, I realize that. its also an automatic and awd with 148k on the clock, really, its just not going to happen without major effort on my part. More than anything else want to see if what i'm experiencing is normal rather than bitch about it being poor.

I have a 50 mile one way commute on the highway, I hit no lights on my way to or from work and rarely get caught in stop and go traffic(once every other week maybe). I live 1 minute from the freeway on ramp with no traffic lights in between. I start my car, let it come down on idle after about 30 seconds and then leave, I rarely sit and let it warm up ever.

I do use the pedal to merge with traffic but after that i set the cruise to a gps indicated 71-73 normally, unless there is something im in a rush for and then I dont question poor mpg on that tank.

What i'm getting with basically 90% highway(i normally drive my wifes car around town unless I need to make a stop on my way back from work) is about 19.5-21mpg average(hand calculated every tank). And I actually think this is a little better than it actually is because my speedometer shows a couple mph higher than gps indicates. Which means its counting more miles that arent actually happening.

On my window sticker for the car it shows 25mpg highway and I know that new and now are totally different. But my instant read out shows 27-31mpg(consistently most of the drive) depending on headwind going down the road. Why such a massive discrepancy? O2 sensors? Fuel injectors leaking? It has index 12s.

Since all my drive is normally highway I was expecting to do a touch better than this, but obviously age and something could be wrong. So I want to hear opinions or other experiences maybe with similar commutes. It has also been stone cold since I got the car here in Michigan(0-30 degrees F normally), so that could be a factor also. No MIL or ghost codes in DME.

Heres a WOT log if it helps;

https://datazap.me/u/typedrew/log-15...&data=3-21

Sorry for the book, thanks for any insight.

If want better gas milage, put a trans tune on it. xHp stage one advertises this particular tune to have better gas milage on the hwy but deliver serious torque in DS and M mode. They say is similar to the Alpina Flash

In theory, adding bolt ons like catless downpipes and removing the secondary cats and putting high flow resonators in their place, for example, makes the car more efficient. However, you drive it more aggressively most likely do to the thrill of it moving that much faster!

[type-dRew]

Originally Posted by Disgustipated

Just thought I'd chime in. You really are wasting fuel efficiency etc by following OEM tire pressure settings, they aren't relevant to your tires or driving. You're AWD, it only makes sense to run 38 front and 38 rear. Get rid of those runflats ASAP, they're junk.

Next, getting a custom tune should add 2-4 mpg especially if you ask your tuner to make it more fuel efficient and to push less boost at low RPM/run it leaner on highway cruise.

Also, try using the Xdelete app from XHP. This will switch your car to RWD mode which will cause less parasitic loss, increase power by 10%~, and should give better MPG overall.

This will cost you $300-400 but will increase power (10% alone from xdelete) and efficiency.

I'll consider bumping front tire pressures up. This thing already rides like a tank, probably wouldnt hurt anything.

I will be getting rid of the run flats, but it has to wait, because it needs wheels as well at the same time. Probably happen after my other bolt ons are done.

I plan on flashing MHD within the next week, probably stay OTS until I do all my bolt ons this spring. Then custom flash for sure.

I will be trying xDelete after spring hits. Getting a lot of use out of the awd still here in Michigan with winter deciding to stick around until fucking May usually

Originally Posted by mweisdorfer

If want better gas milage, put a trans tune on it. xHp stage one advertises this particular tune to have better gas milage on the hwy but deliver serious torque in DS and M mode. They say is similar to the Alpina Flash

In theory, adding bolt ons like catless downpipes and removing the secondary cats and putting high flow resonators in their place, for example, makes the car more efficient. However, you drive it more aggressively most likely do to the thrill of it moving that much faster!

I do plan on flashing xhp shortly, probably before I do mhd. So ill report back if i notice anything from it or the pair together.

I will be making it a bit more efficient shortly with some breathing mods, so hopefully thats the case. And yeah, im sure the first few tanks wont show any increase due to right foot syndrome. lol

Thanks for the ideas.

[mweisdorfer]

Originally Posted by type-dRew

I'll consider bumping front tire pressures up. This thing already rides like a tank, probably wouldnt hurt anything.

I will be getting rid of the run flats, but it has to wait, because it needs wheels as well at the same time. Probably happen after my other bolt ons are done.

I plan on flashing MHD within the next week, probably stay OTS until I do all my bolt ons this spring. Then custom flash for sure.

I will be trying xDelete after spring hits. Getting a lot of use out of the awd still here in Michigan with winter deciding to stick around until fucking May usually

I do plan on flashing xhp shortly, probably before I do mhd. So ill report back if i notice anything from it or the pair together.

I will be making it a bit more efficient shortly with some breathing mods, so hopefully thats the case. And yeah, im sure the first few tanks wont show any increase due to right foot syndrome. lol

Thanks for the ideas.

There's a spot in MHD where you can tell it that you have the xHp flash tune.

[type-dRew]

Originally Posted by mweisdorfer

There's a spot in MHD where you can tell it that you have the xHp flash tune.

That's why i want to get the XHP on the car first. Hopefully start with that this weekend.

[lucasmiller2015]

Originally Posted by type-dRew

Why are the speedometers wrong from the factory? Seems like most tell me the same thing. Can MHD or coding correct it? I hate reading faster than what it should, especially on stock size tires.

Supposedly it's a "safety feature", but it doesn't actually mean that the odometer is counting more miles. The cluster is simply coded to read a higher value than actual speed (I've seen 2-5 mph), but the car does know the actual speed.

However, this "feature" can be coded out. If you have the digital speedometer enabled, setting BC_V_KORRECTOR in the KOMBI module will show true speed on the digital speedometer. It can be fixed on the analog speedometer as well, but I'm not sure of the details. I believe there's at least one thread in the coding sub-forum with more info on that.

[ferocity02]

Cruising ~75mph I'll get about 28mpg according to the computer. At 65mpg I'll would get about 30mpg. Actual calculations were only a couple MPG less than the computer.

[ewicky]

Originally Posted by Disgustipated

Just thought I'd chime in. You really are wasting fuel efficiency etc by following OEM tire pressure settings, they aren't relevant to your tires or driving. You're AWD, it only makes sense to run 38 front and 38 rear. Get rid of those runflats ASAP, they're junk.

Next, getting a custom tune should add 2-4 mpg especially if you ask your tuner to make it more fuel efficient and to push less boost at low RPM/run it leaner on highway cruise.

Also, try using the Xdelete app from XHP. This will switch your car to RWD mode which will cause less parasitic loss, increase power by 10%~, and should give better MPG overall.

This will cost you $300-400 but will increase power (10% alone from xdelete) and efficiency.

xDelete does not improve efficiency, increase power, or do anything of the sort. Not even 1%. OP, you can safely ignore that suggestion.

A transmission flash can lower the shift points, which is good for efficiently driving below highway speeds.

The speedo is intentionally off. The odometer, economy, and other OBC readouts are calculated very accurately. The car then takes the accurate info and, in software, inflates the analog speedometer for legal purposes.

Perfect highway cruising I get 28-31 MPG. >70MPH and it dips down to 27 MPG or lower. Daily driving I get 20-23, with some city mixed in (I live in Seattle but work in the suburbs). I have JB4 and xDrive but not yet a trans tune. I tried JB4 valet mode (target zero boost) but didn't notice an MPG savings. Theoretically valet mode would reduce back-pressure to the lowest possible and increase efficiency.

Although the MPG numbers I cite are from the OBC, I find them very accurate. I usually drive 330 miles and struggle to pump a full 15 gal in, so that's 22 MPG.

BTW the brake pedal wastes way more energy than the accelerator. Seems counter intuitive, but that's the best way to think about it. Avoid braking whenever possible. Maximize coasting. Look far ahead for red lights or traffic. Let off the accelerator soon enough and you may not have to brake ever again

[rsyed07]

I did a 250 mile drive last weekend with cruise control on 83mph which is about 86-87 on the speedo (I have my v read out coded to be exact speed). In between passing slow left lane hoggers and some stop and go on merges I averaged 22 mpg being fbo on 30% e85. The best I have gotten on 93 pump gas was about 24-25mpg for long highway trips. When I filled up I still had about 1.3 gallons left in the tank but the odometer read out 275 miles out of the tank. Normally in city driving the average read out is 16-18mpg with getting 240 miles to a tank on e85.

[Disgustipated]

Originally Posted by ewicky

xDelete does not improve efficiency, increase power, or do anything of the sort. Not even 1%. OP, you can safely ignore that suggestion.

Ok buddy. Dyno says you're wrong, have you actually measured it yourself?



Unless you have proof that xDelete does not decrease drivetrain loss by switching to only 2 wheels?

[ewicky]

Originally Posted by Disgustipated

Ok buddy. Dyno says you're wrong, have you actually measured it yourself?

Unless you have proof that xDelete does not decrease drivetrain loss by switching to only 2 wheels?

You're absolutely right. With the front wheels not turning at all (like in the video), then yes, you reduce drivetrain losses and the dyno will read more power. Of course, in real life, you (hopefully) have all 4 wheels on the ground. The front wheels and their half axles, diff, and driveshaft will drag the front of the car slower just as if the car was AWD.

[///M-N55]

On my FBO N55 86k i get 23mpg when traveling to Louisiana from Texas . And i get 19.9mpg when traveling to school and work ! I'd say i got a pretty healthy car

[ewicky]

Originally Posted by Disgustipated

Ok buddy. Dyno says you're wrong, have you actually measured it yourself?

Unless you have proof that xDelete does not decrease drivetrain loss by switching to only 2 wheels?

Oh, and BTW, this entire thread is supposed to be about highway economy, not 300+HP dynoing. And at highway cruising speeds the default factory xDrive computer goes into RWD mode anyways. And that's a documented fact from BMW. So even if xDelete somehow defies the laws of physics and temporarily sends your front wheels, half shafts, diff, and driveshaft into an alternate universe to achieve better economy, it wouldn't matter because at highway speeds a stock car is already doing the same thing.

[335e92tx]

13IS with OEM catted DPs gets 29.x (both computer and miles/refill confirmed) at 66-67 (and can go 480-490miles on a tank).. 70-to 72 its at best 26.5. I can go just a bit slower an still cover the same time/distance/cost.

VERY few cars can run low 12s and pull that mpg/distance per tank