[EBIINYC]

I've had my F36 428 GC for a couple of days, gas mileage has been significantly reduced and considerably lower than the rating. I am coming from a 201hp turbo 4 cyl so I know what I should expect more or less. My driving style hasnt changed, I was always a pretty aggressive driver so I definitely havent become more conservative or demanding of the car.

I have two theories, 1 the dealership possibly filled the car with lower grade gas. 2, the car could be experiencing some break-in period where the gas mileage is lower.

I filled up the car last night and it seems more responsive and stable, and I'm averaging 15MPG.

[rking117]

15MPG is pretty low for sure. even when i get spriited i still average around 21. Why dont you reset the trips on the odometer and try a 10 mile drive while feathering the pedal and see if it jumps to over 30MPG if not i would suspect there is a problem that needs to be diagnosed.

[KneeDragr]

So Ive read that smaller turbo engines actually get worse mileage than larger N/A engines if the driver has a lead foot. Perhaps you are experiencing that? Either way if the motor is brand new, expect it to loosen up over time.

[EBIINYC]

Well as I said, I came from a 4cyl turbo just like the one I have now. My MB c250 was absolutely amazing on gas mileage, average 23MPG and about 40 on highway drives. So thats why this is surprising. Granted this car is faster and has more HP but I dont think the difference should be so drastic.

Perhaps a reset of the MPG counter would help? Is there a dynamic fuel economy screen that I can see.

[Alan_NJ]

Originally Posted by Igor1080

Well as I said, I came from a 4cyl turbo just like the one I have now. My MB c250 was absolutely amazing on gas mileage, average 23MPG and about 40 on highway drives. So thats why this is surprising. Granted this car is faster and has more HP but I dont think the difference should be so drastic.

Perhaps a reset of the MPG counter would help? Is there a dynamic fuel economy screen that I can see.

Yeah, in iDrive Vehicle Info -> Efficient Dynamics

You can change the graph to show 1, 4 and 15 minute increments.
(maybe another increment I missed)

You should also be able to click the BC button at the end of your blinker stalk to show instant MPG in the instrument cluster.
(assuming thats available on all builds)

[EBIINYC]

Yeah I have that feature on my signal stalk, but I feel like the dynamic screen should work better and give me more details. It seems the car is pretty aggressive as far as the throttle mapping even in comfort mode. In sport it is probably contributing to a decent reduction in mileage. I'm surprised the N55 doesnt get like 10MPG, if this car is supposed to be more fuel efficient and it doesnt seem to be.

[Bmwman325]

Have you reset your MPG reading? also, try calculating your MPG manually and see what you get.

[Michael Schott]

What is your average speed? Are you in or near NYC? It will help us to know your driving environment.

[EBIINYC]

Average speed driving here varies greatly. I would say 30mph streets and about 65-70 hwy. I am in NYC and I commute daily from Brooklyn into lower Manhattan.

[Alan_NJ]

Originally Posted by Igor1080

...I'm surprised the N55 doesnt get like 10MPG, if this car is supposed to be more fuel efficient and it doesnt seem to be.

It does, if in sport with local spirited driving :/
(well, maybe not 10, but pretty poor MPG in that situation)

[thisberob]

I also drive in, and around, Brooklyn, Manhattan, and Queens. Though I have a 535, I average ~12-14mpg when keeping it local at ~20-30mph with stop and go at lights and stop signs. I recently got a 528 as a loaner and averaged ~16 mpg at the same speed and conditions.

At strictly highway speeds, meaning 50-75mph, I get closer to the rating of 29 for my 535.

I know others with 335s that average significantly lower than the ratings given when driving around the boroughs.

I chalked it up to the nature of NYC driving! Hope this gave you some ease!

[EBIINYC]

Well I did a quick reset after I filled up yesterday and either the car is tricking me or the gas mileage has greatly improved, 23.1 MPG yesterday night and today. Also efficient dynamics is showing me a pretty good number as well. Who knows...

[fecurtis]

I'd try just to reset your tripometer with each refill and calculate your mileage manually. If you are still averaging around the 15 mpg range, take it to the dealer. You should NOT be getting that sort of mileage unless you've developed a lead foot.

[EBIINYC]

How does one manually calculate their mpg if I dont know how much fuel is being consumed?

[fecurtis]

Originally Posted by Igor1080

How does one manually calculate their mpg if I dont know how much fuel is being consumed?

Step 1: Fill up gas tank, reset tripometer to 0
Step 2: When you fill up again, take note of the mileage on your tripometer.
Step 3: When you're done filling up, look at the gas pump, it will tell you how many gallons of gas you actually put in. If you get a receipt with your gas, it'll also tell you there how many gallons you put in.
Step 4: Take the number shown on your tripometer and divide it by the number of gallons the gas pump says you put into your car.

So you won't be able to take your MPG on each trip (unless you put gas in your car at the end of each trip you take), but rather your average MPG between fill ups.

[carzaddict]

next time you fill up full....reset the odometer to 0.0. drive around as long as you can until you need to fill up again.....make sure you fill it up full......get the receipt and see how many gallons you filled up.......check your odometer to see how many miles you drove. divide that by the gallons filled
miles driven / gallons filled = mpg

considering you've only had the car for 1-2 weeks...im assuming this is the first time you filled up? or second? my theory is that the car was left idling for a long time, which decreased the consumption. you shouldnt be getting 15mpg unless something screwy happened...for example resetting the consumption and driving the car REALLY hard immediately after.

[EBIINYC]

next time you fill up full....reset the odometer to 0.0. drive around as long as you can until you need to fill up again.....make sure you fill it up full......get the receipt and see how many gallons you filled up.......check your odometer to see how many miles you drove. divide that by the gallons filled
miles driven / gallons filled = mpg

This will prob be the easiest solution. We'll see what happens.

[FSociety]

Originally Posted by Igor1080

This will prob be the easiest solution. We'll see what happens.

Any improvment?

[feng]

I found with mine, my first tank got 11+L/100km (car is rated as an average 6.4L/100km). As I'm on my 3rd or 4th tank with no resets, it's down to about 10.2L/100km. That's with a mixture of town and highway driving as well as mixed modes depending on my mood. The loan car I had was rating about 8.4L/100km after about 6000km, so I'm going to do a reset at about 2000km and see how it goes. I'm sure the engine beds in somewhat.

Apologies for the different units, but it gives you some idea.

[Mike_L]

Thats not bad at all. NYC driving kills economy. I'm getting about 8mpg with the 750, got 14-16 with the A6 3.0T, and expecting about the same or less with the 335. Thats just how it is. Diesels and Hybrids thrive here and gas engines suck down fuel.

[Unit_5]

I think I read in past threads that the oil temp / drive duration affects fuel economy. My commute to work is around ten minutes (~5 miles), driving between 35 and 75mph, and I get ~15-18mpg. Oil doesn't get up to temp until 2/3rd of the way into the drive, so that may skew the figure.

[EBIINYC]

So basically after a month and a half of having the car, I'm averaging 18 and some change. Strangely enough, while this car is more powerful than my last car, I'm driving it slower. My benz was straight up race car status every time I got behind the wheel. Point is, on that car I would get 23-24 MPG, so the lower mpg is strange; all things considered this car is supposed to be a "SULEV" vehicle.