Hey All!

I tried to search this, but I'll admit, I find it difficult to search through SO much info!

Anyway! I've had my '06 Cooper since April '07. I drive roughly 50mi roundtrip to work each day. During the first several months of driving (until about july or so) I was getting a steady 38.5mpg. Then it would taper off a bit...possibly due to my right foot "gaining some weight".

Now the probelm is that since October or so, I've been struggling to make it to the 34-36mpg mark. But I always thought that MPG was supposed to be INCREASE after break-in period...

Since it is colder out, and the possiblity of ice, I have been driving MUCH slower and conservative. So it shouldn't be my driving habits.

I have checked out my tires air pressure and my air filter (stock). Both seem normal.

Could this drop be solely from the colder air temps or something? Any ideas out there? I want my 38.5mpg back!

Thanks!!

 

Different gas? Winter gas? I live in PA and they change the fuel mixture in the winter months to reduce emissions. We have greener trees and grass when it time to golf again but the trade off is lower MPG in the winter.
I would be happy with 36MPG in my MCS 6-SP but I have a right foot the size of Nell Carter.

 

Hmm...I wasn't aware of switching gases during the winter months...I wonder

Any ideas how I could find out if they switch the gas during the winter months? Would the gas attendant tell me?

 

It could be winter gas...we have the same thing here and it does impact MPG. Something else that is a possibility is that when the roads are wet from rain or snow, or slippery, traction is reduced, and this can decrease mileage too.

Other things...are you driving in heavy traffic more often? More stop-and-go driving? Have you changed your air filter?

There are a lot of things that could be the cause, and I have to say I'd KILL to get your mileage (I'm lucky to get around 30 in my Cooper) because I live in a high traffic area.

 

'06 Cooper, no mods, 31 in town, 36 highway

 

I have NOT changed my air filter yet...I'm planning on getting a cai or high-flow drop-in in the near future...so I hope that will help some, but I was hoping to get my stock mpg back up a bit first

 

There is usually a sticker on the pump that says when they change the blend.

 

If they blend you gas with ethanol for the winter, like they do here in colorado, your mpg will go down.

 

Mine only gets 38 MPG on down grades. Like coming back from a Dragon Run.

 

I think it's winter gas blend.

This is the 2 second winter season I've seen my MPG go down by 10-15%. Last year I thought the difference was due to my winter wheels (25 lbs S-lites with snow tires) vs my summer wheels (11 lbs SSRs with summer tires). But this year I swapped my tires late in December and noticed the mileage drop on the last tank or two even with my light summer wheels.

 

My MPG peaked at about 50 degrees when it gets down to 20 and below I drop 20% in MPG

Dont know why that is I have always been told denser air is better but there appears to be a limit to that

 

Did the original poster change wheels / tires for winter? Snow tires will lower fuel economy...

 

Probably due to the winter blend- increased ethynol in the gas. Alcohol has a lower energy density than gasoline, so it takes a larger volume of gas to produce equivalent energy. A gallon of winter gas won't move you as far as a gallon of summer gas.

 

Winter gas is probably most likely. Has your drive time increased? Have always noticed more traffic during school season. Anyway 34-36 is pretty good, I would have to put in a lot of effort to get that.

 

You're being impacted by 3 things:
1. Cold temps mean the engine is on "choke" longer, in today's engines this simply means it's not up to optimal operating temp.
2. Winter gas is used in your region, it has alcohol and does lower gas mileage.
3. Snow tires have greater rolling resistance than all season or summer tires

Add the three together and you will notice the drop!

 

Nope, no change in wheels/tires. (not in the budget until next year maybe )

 

Ah, that makes sense! Minus item number 3, I'm begining to see the drop take shape!

Thanks all!

 

wow, you sure get better gas milage than me.
Stock 06 MC and I average about 31.5 mpg in suburb driving. there is some stop and go but there is generally large distance between lights and not really heavy traffic.

 

My '05 MCa @ 11,300 mi.- 26.5 city / 31.5 hwy avg, using Sam's premium gas. Looks like a substantial difference between the 5 speed and the automatic.