I have a 2009 MINI Cooper S with an Automatic transmission. I bought it in July and about once a day, I'll check the average fuel consumption. It's always between 33.1 mpg and 33.3 mpg. Well today, I checked it and it said 32.8 mpg...about 2 minutes later, it said 31.3 mpg and another 5 minutes or so it said 30.7 mpg. I have been driving conservatively and haven't changed my driving habits at all. Is there something wrong with the car?

-G.B.

 

Maybe the service stations in your region recently switched over to their winter blend fuels. My gas mileage seems to suffer by 5 to 8 percent when that happens, and the observation has been consistent for my five years of ownership.

 

Hmm...I never knew there were different fuel blends depending upon the season. That could very well be the case though. Thanks!

-G.B.

 

Had to run an errand this evening. I checked the mileage again to see if it went down any, it's currently at 35.8 mpg...it's never been that high. Is the computer acting up or...? I haven't changed my driving style at all.

-G.B.

 

There is only one way I trust for mileage miles driven divided by amt of fuel used, computer readouts no.

 

That's a great tip actually. I need to stop relying on technology so much. Thanks and happy motoring!

-G.B.

 

go to Pure-Gas.org maybe ethanol free will help

 

There is more to life than fuel mileage.

X2 on the hand calc when you do want to know.......

 

your trip computer got reset. Wait like 200-300 miles and see if it goes back to normal.

 

This is what I think as well. It shouldn't be jumping around that much to be honest. Sounds like it was reset or the power was cut and it reset. It should settle in very soon.

 

Agreed... just after reset, the trip computer is essentially starting over with new data, and there will be some wild variation before it all averages out.

BTW, I agree with the hand-calculation method. I've always recorded mileage data with every fill-up, using a notebook I keep with the car, and once in a while I sit down with the calculator and figure MPG. It's a good way to spot trends, such as decreased efficiency during the winter. Gil-galad's right about the fuel formulations changing during the colder months, but another factor is that the engine computer enriches the fuel mixture for winter starts - a task which was handled by the choke back in the good old days. So you're not only running a different formulation of fuel, you're using more of it until the engine warms fully. My MG has a manual choke (added by a previous owner - it was originally automatic), so I've been able to experience first-hand the difference a richer mixture can make when it's cold out. It's no different now... just that a computer chooses the optimum mixture for the conditions, rather than the old fashioned seat-of-the-pants method.

Spridget