Sounds like me . I monitored the boost driving to get food and it varied from about -10 to +15. Not totally sure about the numbers. Tire pressure might be low, I would have to go about checking that. It probably is, as I havent checked it in a long time. Tomorrow then

 

Oh if you are boosting 15lbs you are damn near at WOT. So yeah that is going to kill your MPG.

 

Yup. It seems alot of people get around 25 saying they drive pretty hard, so not sure what they're doing or what my driving style would be called. Ill make sure to check tires tomorrow.

I saw on the AP forum that some people were geting 20 psi

 

Yep not unheard of to run 20psi with a stage 3 tune. Though there is a lot of cut issues with Alta's tunes but, it is what it is.

 

Ive noticed the cut isnt as bad when I shift and lift off the throttle a little. If 20 psi is for stage 3, it looks like exhaust is next on the list. Im also sure that my speakers make the mileage worse

 

22mpg with the on board computer, 08 cooper s auto

Tires run at 38psi.

No idea at all why it's such bad mileage. My wife drives it slow and it's all city traffic...

 

Bad traffic? Probably lots of idling. Not moving, but with engine just idling, will REALLY do a number on fuel mileage (which is why cars are starting to come with an auto start/stop feature).

 

That autotragic isn't helping either.

 

I'd say that's about right for city driving. Here's what I've gotten the last 3 fill-ups. BTW, the lower number on the bottom of the screen shot is what you get from using ethanol gas (even though it says ethanol-free - I don't use the app 100% correctly). I always get premium and unless I'm in a pinch, ethanol-free. You do get better MPG and I think you get a little better 'punch' out of the car. It's harder to find of course, but you can use pure-gas.org and the Pure Gas iPhone app to help you find stations close to you based on your GPS.

 

Not hard to believe at all. I had a '99 Saturn SC1 and putting a roof rack and a couple of bikes on it was like installing a wind dam. MPG sank like a stone and so did what little power the SC1 had in the first place. Aerodynamic drag!

 

pure-gas.org

 

I'd have your car looked at. That's not right, even for hard driving.

 

I don't understand getting an auto with a Cooper, but that's me. I haven't owned an auto yet...

 

Driving a 2013 MCS, my OBC is giving me a current average of 32.6mpg...and on the highway, doing 60mph in 6th gear, I was able to maintain ~ 45-50 mpg.

 

It is like dying a slow death.

 

Just went to dealer, timing chain tensioner replaced. Tires were filled, so maybe it will get better. I also think that my short drives with lost of stop and go traffic kills it. That plus me driving and california gas= bad.
Im going to see if I can monitor the ecu without the accessport installed because i was getting o2 numbers of about 1.5, which is supposedly rich. I think .5 is 14.7 afr

 

I average 33 mpg during my daily 20 mile commute. Stop and go traffic will definitely kill it though...

 

I typically average around 24-30. I drive the hell out of the thing so that's A ok with me!

 

My MPG keeps creeping up.

 

Here's something to trick you all out.

 

You get higher variations with smaller fills, in my experience. Going to the extreme, if you only put 1/4 of a gallon in, the few drops in the filler hose are a significant percentage of the total.

But regardless, 42 is pretty darned good!

 

In the interest of full-disclosure - I had a trip on the Natchez Trace parkway on Saturday where the speed limit is 40mph for the first ~15-20 miles, then 50mph. Keep it in fifth gear and no sport mode and you'll get a huge boost like that.

 

Sounds about right with 60/40 highway/city driving and a fairly light foot. You don't mention transmission type (among other things), but I'd say from the numbers it's a manual and not automatic, because I'd expect a bit less with an automatic.

 

Wonder whats up with this crap.

 

To all the automatic haters. I know their not near as much fun, but Auto Trend reported the auto about 5 tenths quicker than the manual, 0 to 60. Wifes 09s averages 30 mpg city short trips.