Gas mileage getting progressively worse

[foosh]

All these comparisons of gas mileage are silly. There are far too many variables to draw any conclusions including, but not limited too: driver's technique, city/highway mileage, amount of traffic congestion, number of starts/stops, etc., etc.

The only way to draw any meaningful conclusions is to put the multiple identical cars on the same route over many different days with the same driver, replicating his/her driving style as closely as possible..

[Radiation Joe]

Originally Posted by Yervais

Our stock air-boxes are extremely good at flowing air in... so much that sometimes your filter could get clogged in with debris... so thats why you might be experiencing a decrease in your range...

Either open you airbox to see whats up or try this... buy an aftermarket air filter I got the ape performance one... I know this will sound crazy but they improve the car quite a lot for city driving due to better throttle response and milage goes up... with the stock filter I used to get 240 miles on one tank on shell now with the ape air filter I got 270-290 and very nice throttle response...

So give it a try... this is on a 2009 E92

Don't listen to this guy. He has no idea what he is talking about. An air filter change will NOT improve your mileage. Never. Ever. Oh I forgot, if you happen to be driving a car with... err, what are those things called.... oh yeah, a carburetor, you may get an improvement. Last time I checked, my car didn't have a carburetor.

I don't know how many miles the OP has, but my mileage fell off a bit before my 30k mile service. New plugs took care of that. Also, all other things being equal, your car will get better mileage in hot weather than in cold.

[dgbos]

Mine also seems to be getting worse and I have an aftermarket air filter. I average ~15.5 and 190 miles per tank. That being said I find it difficult to not stomp on the gas frequently so I guess it is worth it!

[gr8000]

probably it is because you get accustomed with the car and want to push it harder and/or more frequently, which causes the lower milage!!

[Khurram]

Thanks for all the replies guys. I guess I'll keep watching it and see how it goes.
Could be just a few extra trips around the beach like you guys mentioned. My average mpg over my last 10 or so fillups is 12.9 mpg according to the computer.

[mkoesel]

Originally Posted by J08M3

you'd be surprised what a couple of really short drives around town can do to lower your MPG. Do an extra one of those and even just slightly less on the highway or longer cruising drives and you can easily see a drop in MPG

+2

[MJC///M3]

i'm getting progressively better...at 16.2 mpg right now....but I dont care about mpg...if I did..I wouldn't be in command of a 414 HP V8.

[JCtx]

Originally Posted by foosh

All these comparisons of gas mileage are silly. There are far too many variables to draw any conclusions including, but not limited too: driver's technique, city/highway mileage, amount of traffic congestion, number of starts/stops, etc., etc.

An important one is oxygenated fuel, which many cities are required to sell 6 months of the year, and it hurts gas mileage due to less energy content. Plus don't forget ambient temperature and humidity. Like you said, too many variables to even compare the same car and driver. Good day.

[ScheerSpeed]

you should have kept the carbon leather trim, it must have been that much lighter

[bryanr]

I was getting about 16 mpg on mixed local roads and 2-lane highways. I'd been keeping it in 4th most of the time for the sound/feel. On the last tank I tried putting it in 6th whenever I could (55mph+) and ended up at about 19mpg. That included some pretty awful traffic jams too.

I've tried resetting the mpg while driving to get real-time measurements (wish it could just provide that in addition to the running average)

In 4th, I get about 16 - 18 mpg on the highway. In 6th, it's as high as 24

gl

[gthirtyfizle]

Originally Posted by Khurram

Thanks for all the replies guys. I guess I'll keep watching it and see how it goes.
Could be just a few extra trips around the beach like you guys mentioned. My average mpg over my last 10 or so fillups is 12.9 mpg according to the computer.

Now this is what im talking about.... drive ur car guys....

I dont think i have ever gotten passed 13mpg lol. ATM im at 12.6 i believe

[NewM3driver]

I was getting 16.5 miles per gallon per the on-board computer. Then it dropped to 15.5 and then 15. NOW, WITH 7000 MILES, I'm struggling to get 14.5.

What concerns me more is the fact that I am still hearing a drive shaft vibration at low rpm and now I notice a "clunk" every time I let the clutch out. Something is going on... time to bring it in for service.

[Steveo58]

190-200 for a tank is really low. I'm getting 260-290 on average. Typically get 18.5 to 21 mpg. And I drive with my right foot. Car has 28,000 miles on it now too...

[bobbyd1961]

what is your miles per gallon. mine is a steady 15.8 70 - 30 city to highway

[kbk_75]

My car is pushing two years old and I have also noticed that my fuel consumption has increased over the past one year compared to the year before.

I live in Bombay, where the traffic is horrendous, and I am quite heavy with my right foot, with the result that I rarely see 200 miles on one tank!

[moog55]

Originally Posted by MJC///M3

i'm getting progressively better...at 16.2 mpg right now....but I dont care about mpg...if I did..I wouldn't be in command of a 414 HP V8.

+1

i've never done better than 13.8 mpg, but my driving is 99% stop-and-go city driving.

[JCtx]

Originally Posted by NewM3driver

What concerns me more is the fact that I am still hearing a drive shaft vibration at low rpm and now I notice a "clunk" every time I let the clutch out.

These cars are 'clunky' man. I hear that same clunk since day 1, but only when I get sloppy with the clutch. And you can 'hear' a vibration? A vibration is felt, not heard . Are you talking about gear whine? Describe what you hear. And don't take your car in unless you can consistently duplicate your issues, or you'd be wasting your time. Good luck.