Horrible Gas mileage

I own a 2011 Mini cooper countryman s all4 and here recently it has been shredding alternator belts, I figured out the issue was a pulkey I replaced the pulley and everything is good with that, but now my mini gets awful gas mileage, I can drive 10 miles and it’ll say I went 40 miles. The gage isn’t the issue, I’m not leaking gas anywhere, I am leaking oil VERY slowly into the engine bay. Any ideas on why my mini is Drinking gas? I’m having to fill up after almost every drive!

Is the check engine light on? Just how many miles per gallon are you getting? Is this something new with this car or did you just buy it?

No check engine light on, I bought the car used ive had it since October this is a new issue it was like after the belt snapped due to the pulley it started having issues one after another. Im not sure about the miles per gallon at the moment, i drove to work filled up before I drove went 65 miles and had to fill up again before I drove back home and when I got home so another 65 miles it said I had 7 miles till empty.

But how much fuel did you put in ? If you disconnected the battery maybe the read out for miles to empty needs to reset . Are you saying the trip distance does not match the odometer for the distance you drove. If you really used a full tank in 65 miles you may have a serious leak that could result in a fire .

I filled it up, everytime i put gas in it, it actually needed the gas so the odometer wasn’t wrong. I’ve not seen any puddles or anything under my car or under the hood that show me its leaking anywhere, how else could I go about checking for a leak, i would think with it leaking that much gas id see a puddle or drops somewhere.

The thermostat is stuck open/broken


Bad coolant temp sensor is telling the computer the coolant temp never gets up to operating temperature when it does.


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How would i go about seeing if this is the issue? Like I said it isn’t throwing any codes or anything just has AWFUL gas mileage!

10 gallons of fuel to drive 65 miles? Is your car leaving a trail of black smoke?

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No black smoke, it doesn’t smell of gas when I start it or when its sitting at idle, no puddles or spots under it.

Find a good independent mechanic and pay them to diagnose the problem(s). It will be money well spent.


Be prepared to spent a boatload of money to get it fixed, though.

Mini Coopers don’t have an “affordable” reputation. And I fear that you may have inadvertently purchased someone else’s problem.

Sorry. Good luck to you.

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Thank you, my husband and I have quickly realized this and would like to fix it so we can trade it in for something else!

you filled it to go the 65 miles to work, I don’t care how much gas it took at this point.

You filled it again to go home, How many gallons/dollars of gas did you put in to go home ?

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It wouldn’t hurt to check for a seized brake caliper, although most likely that wouldn’t result in fuel economy that’s this bad.

Yes, that’s the only way to determine MPG. 65 miles travelled isn’t very many - so any variation in when the gas station’s shut-off clicked will be magnified - and the MPG figures not very reliable.

Better to fill up after more miles have been travelled - most cars can go at least 250. Fill the tank and write down your odometer miles. Drive 200+ miles. Fill up and calculate the MPG. Then do it again after a good 200+ miles. Add up all your miles since you started this test. Add up all the gallons you added to the tank after (not including) that first fill-up. That will yield a more accurate MPG figure.

I understand that, but did she put in about 2 gallons or about 10 gallons ?

The only reason she filled the second time was because of the 7 miles to empty reading

If it only took 2 gallons, the problem is with the gauge.

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2 gallons for 65 miles sounds about right… and the miles-to-empty gauge sounds wrong.

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I just noticed this comment, but I can’t think of any way in which this apparent odometer malfunction could be related to the fuel economy problem, so this is very confusing.

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It wouldn’t cause the car to consume more gas, but it could cause the onboard MPG readout to produce bogus readings, thus leading the OP to think that it was consuming more gas.


If the odometer says the car went forty miles when it actually went only ten miles, the calculated MPGs would be extremely good, not extremely bad, as reported here.