[cecilseahawks]

I am getting ridiculous gas mileage in my 07 335i. I'm averaging 19mpg with a lot of highway driving. The problem is everytime I even breathe on the gas pedal, the mpg drops to between 6-8. I have had tc cars before, some with much more power than this and this is by far the most thirsty of them all. I do have a jb3, but I have tried map 0 and still get the same results. While on the highway, the displays shows around 16mpg most of the time. I'm starting to think something is wrong. Any insight?

[hpowders]

With my 2007 328i, I got 20.6 mpg with Steptronic in DS mode-all highway driving for 186 miles.

Your engine is more powerful.

Ya gotta pay to play.

[Chriztofor]

I would try using Chevron Techron fuel injector cleaner.

[Got_da_booze]

Your MPG is definitely off. I've had up to 30 MPG on the highway with speeds up to..., we'll just say I was speeding on a few occasions

[focusse]

im doing 19mpg on my 330xi kind of sucks when my previous car did 30-35 mpg...... but you have to pay to play

[Couch]

How much traffic is involved with your highway miles? What speed are you traveling on the open road? How many miles per tank?

[Kroy]

OP, for a tuned n54, your MPG sounds normal. I notice that I get better mileage in map 0 but it's not very noticeable in short run tests. You need to test for at least a week or two (better if you test a whole month). My car for example can get anywhere from 250-300+ miles to the tank depending on traffic, but every month my average smooths to around 18mpg.

That said, 16mpg while cruising on the highway does not sound right. If you're accelerating, then yes it sounds normal. But if you're maintaining speed, you should be getting 25-30+mpg. Again, you give it any gas, the MPG will drop to like 15 and that's normal. Try using your cruise control to help test. If you have navigation, use car data to check your trip information.

[tony20009]

You should have your car looked at. I get 30-31 on the highway and 28-29 if I'm aggressively driving.

[Php]

I don't think it sounds that unusual, maybe just a bit low.

[fdriller9]

The fact that your mpg fluctuates from an average of 19 down to 6-8mpg means something is wrong with a sensor or a computer in your car.

I just drove 100 miles from NJ to Philly and my MPG went from 14.6 to 15...I have a lead foot ok. MPG should not fluctuate that fast unless you just reset your OD or unplugged your battery and there is no data for the computer to accurately calculate a MPG value.

Try cleaning your MAF but a dirty MAF will rarely make your MPG fluctuate like that.

[Orion4]

Your MPG is definitely off. Is this based on what the mpg readout is displaying or are you calculating actual between fill-ups.

My 08 335i has been consistently getting 29-30.5 mpg on long distance trips up and down I-95 from RI, DC to Melbourne, FL. Lowest was 27.5 with lousy weather and heavy traffic. I have a pretty heavy foot so this is not crawling is the right-hand lane in 6th at 1200 RPM.

In the immediate area with mix of city/highway, I average 20-22 mpg.

I've been running a JB-3 PnP in Map 5 that entire time. So something is definitely amiss!!!!

[Cosmop]

I've got a 2009 335i
With city driving a get 17-18 mpg. If it's a long higway trip it will go up to 25-27 mpg. It's not great in the city but like someone else said, you have to pay to play

[Blubaron79]

I get WAY higher MPG than that. I have xDrive, and even when driving like an ass, I get 21+ MPG.

[bugmcw]

I drive pretty aggressively in Atlanta traffic and still average over 20mpg. Yours isn't right

[jw95275]

I think OP is talking about the realtime mpg numbers being 6-8, not the running average. I get 20mpg with 1/2 highway and 1/2 street, but I'm rarely aggressive.

[John 070]

You need to cover some miles for the mpg to be reliable. If you set your cruise for 70 mph, and drive 15 min. without slowing down, and you don't see 30 mpg, there is something wrong.

My mileage seems to have improved after my VANOS intake solenoid was replaced, but that's probably the placebo effect.

[techlogik]

Have you tried a simple manual calculation from when you fill up/how many gallons, then how much it takes to fill it again, divide by mileage and get the pretty close estimate of MPG??

I get around 22-23 mixed driving in my 335i.

[username604]

try resetting your mpg's. Anything past 1/3 throttle is 6mpg because you can't keep that up for that long. I was getting 17.8 mpg (when i first started using it i had ~16 which i found was depressing), and after i reset my mpg's, i was getting 20-22 depending on the trip. I realized that the time you spend idling *kills* your mpg's and the car counts that time as 0mpg. (which hurts the average)

[madeinhongkong]

I would check tire pressure, install new air filter, and dump in a bottle of Lucas fuel injector cleaner first.

[SpmnE9zero]

I, in two years of owning my car, have never payed attention to my mpg's once.
Oh well, I guess I just figure.... what is the point, it is what it is. Kinda like looking at the weather channel, why bother?

[onebadmofo]

Your O2 sensors may be going bad, scan the car or take it to dealer. I average 21MPG in the city. And you know how I drive? I have only two positions for the gas pedal - on and off

[bimmer_335]

Take out JB3 and drive for a week... then compare your numbers. I have no tune and I get close to 22 mpg... with the tune 19 is not that bad.