Hey Everyone,

We bought a 2014 F56 "Justa" new a few years ago and our MPG has been going down steadily. We originally average around 34mpg since we regularly drive in green mode with most of our driving being at freeway speeds.

As of lately, we have been averaging closer to 24 mpg and the only thing I can think of is the constant updates Mini is adding to our computer. We purchased this car purely as a good mpg car for the price and have put about 28k miles on so far.

I know carbon build-up used to be a problem, I'm wondering if I need to brace for some bad news like that. We have been consistently using 91 gas and haven't missed a service appointment. I should also mention my girlfriend does most of the driving in this car and is always in "green" mode with a very light foot.

 

You may be doing this correctly, but I would fill up and reset your trip odometer. When you fill up again take the miles you have driven and divide by the number of gallons you put in. That is your true mpg except for slight errors from filling the tank a little more or a little less than the first time you filled up. I don't thing the computer is very accurate.

 

Admittedly, I have been using the computer generated number and just resetting it at fill-ups. What first made me take notice of the number was the increase in fill-ups.
So I think my first step is to do my own math and then second figure out why I am filling that car more often.

I am curious to see what figures others get. When we bought this car, there was some dialogue about not being able to disclose safety rating or mpg because it hadn't been put out yet.

 

Something is wrong with your car if you are driving as you describe.

When I first got my car, I played around with green, mid, sport. In the end, being a manual, unless I really want to get on it, I just drive now exclusively in mid.

I consistently get between 37 and 39 mpg on the computer, and when I divide miles by gallons, it's about 1.5 to 2 mpg less -- but I also pretty much keep going a couple of more times after it clicks off.

And on MTTS, the first 3000 miles (going up and down the Rockies driving from San Diego to Sturgis), driving speed limit + up to 5 mph over, where the speed limits often were 70, 75, or 80 mph, my trip computer was showing 41.2 mpg for the 3000 miles.

Something is wrong with your car ...

If you have an auto, maybe it's not shifting right and hence your running higher rpms.

 

Thanks for the reply. I'll try to respond to everything here.

First off, the car is an automatic. Secondly, my girlfriend drives it exclusively in green with me driving it in green on the freeway and mid usually around town.

When driving it long distances like you described, we have gotten about 37mpg between Vegas and LA. That was also about a year ago.

As far as the transmission.. When in green mode, it shifts us very early. Sometimes it seems like it barely makes it past 2200rpm. It is funny you mention the transmission because I drove the car in sport mode the other day and found it to feel odd. It was shifting rather clunky and the acceleration was not very linear. I'm not sure if that is because I just haven't driven it hard in awhile or something is wrong. It had a lot of dead spots along the power band and nearly felt like it was surging.

 

That sounds pretty typical characteristics of driving in Sport. It's probably even more pronounced to you if you're always in Green. I usually drive in Sport, and putting it in Green feels like the car is dead and won't accelerate. I often compare the feeling of the car while driving in Sport to being in the car with someone that can't properly change gears in a Manual.

Still... you shouldn't be getting THAT much worse of gas millage from a car that's only a couple years old.
Do you check your tire pressure regularly?
What about your alignment?
Maybe try a fuel cleaner additive? What brand of gas do you usually use?
Possibly a slow dying fuel pump or clogged fuel filter?

Anyway... Your car is still under warranty yes? I'd take it to Mini to have it checked out fully.

 

Yes, the car is under warranty. To be quite honest, I hate the customer service at my only dealer in town. I dread going there because of that. I will set that up however.

Tire pressure is not checked regularly but I will check that tomorrow. It has only been about a few weeks since Mini had it last. They had to replace the lower control arms for a second time which also included a front wheel alignment.

We use only Chevron gas in it (91 Octane)

 

Keep us posted on your results. My '14 manual F56S consistently gets 35 - 37 mpg during the summer months, and I'm never driving in any mode considered "green". Anything less than that on an F56 Cooper in green mode with automatic is telling you something's not right. Check your mileage again manually after using a full tank of gas and then if it's still poor, get it to your dealer and explain your results. Don't wait - that won't accomplish anything. Good luck!

 

I'm getting 30-31mpg around town and just over 36mpg on the highway using cruise control at 70-75mph on my '16 JCW auto in green mode. Calculated using the miles driven divided by gallons needed to fill up. Just turned 5k miles this weekend.

Mike B.

 

Here is a quick update on this.

I ran the mpg manually and am almost exact to the computer on this last tank. My mpg was 26 for around city driving in "mid" exclusively.

I have an appointment with Mini tomorrow because my lower control arms are clunking once again. I am also going to have them check why my mpg is low. I also checked tire pressure. Although it wasn't where I would like it, it wasn't extremely low either. I believe they were between 37-40psi before I filled them.

 

I'm only at like 800miles so far, but I averaged 30-31mpg on my last two tanks. Not sure what the first looked like because I didn't fill it. I'm usually in sport mode with the exhaust flap open.

--Matt

 

To add to this, the car is now turning over for at least double the time before starting. It usually zips to life in half a second or so. I would estimate we are closer to 2 seconds all the sudden.

 

Here is the update from Mini today regarding gas mileage.

They found no fault codes and they checked the fuel pump. He said they can't do anything else unless they kept the vehicle for a week and tracked the gas mileage.

It seems like a pretty canned answer to me with no real results behind it. I obviously knew there wasn't a check engine light on when I came in.

 

My last tank was 41.2 mpg. That is actual mileage, miles traveled divided my gallons used. The worst was 34.5. Overall would be right around 38.6. I live in a rule area where traffic is not much of a problem. Sport mode definitely drops the mileage. My Mini is the 3 cylinder.

 

The fuel pump's gonna go bye bye IMO. If you have trouble starting it first thing that's what my R56 did before I couldn't start it at all. Not sure about the gas mileage, but 24 MPG is not normal for that car. I get 26 in town leadfooting my JCW!

 

That really sucks. Since it's hard to tell gas mileage in city (with signals and traffic), how about trying 100% highway for like 10 miles when the car is warm and there's no traffic?

You can use the trip computer in the car as it's not too far off from actual mileage. Just reset the gauge before entering a highway, then get on highway drive on cruise at 55MPH (or whatever the speed limit) for about 10 minutes and get off the highway, check what MPG you get. You should see at least 40MPG if all the conditions I mentioned were met.

I also have a F56 (2015). At 55 MPH I can get 45 MPG. At 65 MPH mileage will be closer to 40 MPG. This is with 10% ethanol gas (which has less energy than non-ethanol), premium. I set the tire pressure between 36-40 PSI, use the old school stick-gauge to check the PSI.

While your car is at the dealer you can also try testing the loaner if you get the same type of car.