I have an 02 MCS and I drive 60 miles roundtrip for school every day, sit in traffic about 10 minutes a day give or take, and I have various city trips for work and other nonsense. I drive conservatively most of the time, shifting at or just above 3k for every shift. But who am I kidding. . . I get on it pretty good atleast twice a day, it's just not nearly as fun at all with the snows on it.

My car has 101xxx miles on it and this afternoon when I filled up with 91 Octane Shell "V-power" which I always use, (I wish I could use 93 Octane but it's neary impossible to find in CO), I got exactly 30.76MPG's

That is with my Holey's (winter tire set up) and with letting it idle every morning or anytime when it's dead cold for that matter, for about 5 minutes so it can warm up a bit. I always, always let it warm up a bit in the winter here as it gets down to 15 degrees F regularly, and I feel bad enough about driving it when it's that cold outside as it is.

It's really all about your driving style. Watch this film: http://www.youtube.com/watch?v=dKTOyiKLARk

 

Yup....and the tire size/rim combo makes a big differance....
It is easy to see how far off the speedo and the odometer is when non-stock size tires are used....sure it make stay within 3-5%, but that can make a pretty big differance when calculating MPG. Same goes for using the trip computer...they all seem to be 1-1.5 mpg optimistic compared to doing the old fashioned fill up the tank and do the math for the mpg!!

 

2004 R53 MCS 6 sp. Drive it like a road rage maniac/race car driver. I run stock R84 X-lite with 195/55/16 Potenza RE760 @ 36psi.(nitrogen fill) Hand calculated 330 miles 12 gals. 91 octane. on average. I have gone 360 mi. on a tank full in the past but after rescuing my friend @ 352 miles on his tank on the side of the road I stopped pushing her. I've been down this road on forums before. Especially the diesel forums where folks claim 20mpgs or better while I get 11.4 mpgs. Diesel folks are the biggest optimists.

 

I've recently noticed a 2 mpg decrease in my R53 as well, with no difference in driving style or variables within the vehicle. (Was around 27...now around 25mpg. Car has 12K miles on it.)

 

im getting like 22mpg on the past 2 tanks in my 02 MCS which i think is really poor, i just bought the car with 48k on the clock. it looks as though the car has been extremely well maintained though. so i wonder what could be the issue? any ideas guys. btw the driving is like 80% highway, im very experience with a manual and i drive like a granny most the time.

 

Most folks see a decrease from the winter gas mixes....
Also warm-up's reduce mpg.
Without realizing it, the a/c gets run tons...if the temp is auto, it may be on, if the defroster is on, it is on.

 

After changing my spark plugs, my gas mileage jumped up about 4-5 mpg so that could be a problem some others are having. Especially if you just bought the car. Who knows how long its been since they have been replaced?

I'm planing on giving my MINI a Seafoam treatment to see if my mpg will increase at all. Hopefully that will help me get up into the 30's range everyone seems to have!

 

A lot of getting mpg is basic mataince, but some is good habits...good luck with traffic or lack of, and basic things like manually turning off the AC, which is usually on auto mode when not needed.
Watching rpms on upshifts help, but watch the obc, often due to gearing, 6 gear is not the best unless you are going 65+ mph...remember both 5 and 6 are both overdrive...try to push too tall a gear, and mpg goes down....

 

I don't think winter fuel mixtures are an issue anymore (E10 all year round) (unless they're sneaking this E15 crap in on us and not telling anybody...it would not surprise me). Also, in my case, I have manual climate control, so there's no issue of the A/C running when I'm not aware (just the way I like it).

Personally, I've found that 50mph is fine for 6th gear, assuming slight or no inclines and slight or no acceleration.

These cars are VERY sensitive to driving style (and traffic patterns...good point, about "luck with traffic"), with reguard to fuel mileage. Since I read this thread, I've been paying closer attention to how I'm driving and mpg went back up to 26.7~28.3, from 25.0~26.4.

 

The mixture of chemicals that comprise the fuel is changed seasonly to change the vapor preasure of the fuel...summer fuel tends to be a a mixture of slightly heavier chemicals...and often has a few more btu's..Or more simply put more energy....(and the reverse is true...to achieve the higher level of evoprastion, or vapor preassue, a slightly lighter, more volatile mix is used for the winter...gasoline is many, many different compotents) once upon a time, ethonol was one of the things added or subtracted to the fuel to adjust both the octane and the vaporpreassure...now as a mandated additive, other compotents are tweaked to achieve the same results...

 

Congrats on the MPG gain! It leaves you with more $$ to spend on mods or to spend on fun motoring!!

 

I did not know that; and thank you...I'm working towards a whole six-pack!