SillyBear

I need your input on my car fuel performance.
I purchased my car Nov 1, 2004, Gas mileage was good. I got 410mpg on the full tank of gas. After 4-6 gas refill, my full tank gas mileage drop down to 380, then 350 then 320 mpg. 2 week ago, I'm getting 300, this time my last full tank of gas last me only 285-290 mpg. I'm using the gas type 91, same driving condition. Both on highway and city driving. I took my car to the dealership and they said the computer shown nothing wrong with my car. I'm very frustrated and believe my car is a lemon.
What should I do from my car to remedy the problem?
BMW certify this car 19/30 average mpg.
Full tank of gas is 18.5 gallon

285 mpg on my car / 18.5 gallon -->that mean I'm only getting 15.4 mpg.
This is as bad the any SUV!!!
Those number not include I'm driving on the freeway.

AHHHHH!!!!!!!!
Please advise.......

Iceman

Was you car getting a software update? If so... The transmission needs to learn how you are driving again.

My mpg went up dramatically after a software update, but after two weeks it was all OK again.
Als, don't forget that in winter time the mpg is a little bit higher, espacially when making a lot of short trips.

SillyBear

No, this is the 1st time my car at the dealership.
I purchase this car close to 2 month. I only has 3001 miles on it.
I also waited to for the 1200 miles break in time before I step above 100 mph.

Hormazd

u Silly Bear! (sorry couldn't resist)
I really do not think you have a lemon. Lemon is what JDN and SueBMW have.
Your gas mileage is quite normal. This is what I think. Correct me if I am wrong.
1) You are basing your post on the miles to empty figure on the dash.
2) This showed 410 to empty when you took delivery of the car.
3) It now shows 380. to empty.

Problem
There is no problem. Calculate your actual mileage at the pump and you will be happy. Driving in SoCal, freeway or not your mileage is normal

Solution
After your next full tank. reset the onboard info for MPG. This is done in I-drive.
Then cruise on the highway in top gear for 10 miles at 55.
Your miles to empty number will go back up to 410.

Unless you reset the Onboard info, the car calculates a rolling average. So if you drive 10 miles on surface streets in stop and go traffic (12mpg) the 10 miles on the freeway top gear (25mpg) It will recalculate your miles to empty at 18.5mpg. Now if you only drive 5 miles on the freeway then it will calculate at 16.3mpg.

The key is to reset the onboard info to get accurate results.

SillyBear

That is what I did.
Each time I refill the gas tank. I reset the gas tracking switch on the dash board, not in the the I-drive menu. Still my driving condition is normal. I should at lease getting 340-380 mpg. The gas mileage total I quote are from my gas tracking meter, not the computer shown how many miles until the gas tank is empty.

beewang

Perhaps you should Slow TFD and back off on the throttle??!!

beewang

kscarrol

By gas tracking meter do you mean in the iDrive? If so, the MPG computations are generally not very good. I assume you have also done it the old fashioned way: filling up, reseting your trip odometer, driving to your next fill up and dividing miles by number of gallons needed at next fill up. I have found this is still the best method and that the BMW onboard computer is not very good. If this is how your doing it and you have seen this kind of drop in mpg, I'd say you are having some issue with the car. Don't know what, software, tuning of some sort, but seeing this kind of drop, assuming your driving style is not more aggressive (using DS etc), seems to be a problem. Don't what to tell you about your dealer's reaction, but keep after them.

The "gas tracking switch" on the dash is just resetting the trip odometer. Resetting this will not impact the estimated miles till empty, either on the dash or in the iDrive. I am not surprised to see the estimated miles to empty drop since delivery as it is computation based on recent avg. MPG. When you took delivery, the avg MPG driving off the boat and around the dealers lot was very high (assuming you bought the car without it having been test driven by others). As you drove the car around town, likely more aggressively than it had ever been, the estimate till empty will drop.

Hamann5

Well im quite the oppsite... When I fill my car up the computer says 380 MPG till empty... but when I start driving (and I do tend you push it once I fill up) that puppy jsut keeps going up!!! Hell I've went from 380 to 415 once... but after I peaked at 415 that thing just fell and fell till I was back to where I started...

paasan

The MPG estimate shown on the OBC when your tank is full depends on how your consumption has been for the past X miles/kms.. as a result it will keep changing with your driving style. The calculation isn't based on a constant consumption.

roost

You don't think it's that 135mph trip to vegas that killed the MPG