Just took delivery of a 2011 MCS last week and noticed that the trip odometer + miles remaining til empty = 460 miles. However, it says I'm only getting 28mpg. How could that be? Would resetting things re-calibrate it?

 

Since the car is still new, i believe it takes some time for the computer to actually calculate the mileage. Mine was the same way when I first rolled off the lot. By the 2nd or 3rd trip to the gas station, it should be normal

 

My 2010 Justa Cooper automatic is 5 months old and the MPG computer is off by about 10mpg. Ridiculous. My wife's 2008 S and my previous 2008 Justa were also off but only by 3-5 mpg. There's almost no point in having that silly thing installed if it's that far off.

As far as the miles remaining display, that's slightly more accurate, I think. But once it tells me I have less than 80 miles left I find the 1st gas station I can for fear it too may be screwy.

 

Yeah, they are never very accurate. Some other car brands have been much better in the past.

The only way to really measure it is to keep track of gallons in and mileage.

I keep a spreadsheet of all that data, but I am a geek. I warn you, if you start keeping a spreadsheet of your gas expenditures, you will be frightened of how much you spend year on year.

 

You are a brave soul - I don't even look at the price - just grab the receipt and run. But I do track MPG on trips, never around town.

What I like about the hoaky MPG readouts is resetting it right before you exit the freeway......... 99 MPG for a while. Yea real accurate. NOT.

 

On the scangauge, it reads a different instant MPG than what's read on the car. But the SC also corrects when you fill up.

Go figure?

I also keep a spreadsheet (used too, now it's an app on my phone) that keeps track of things. I love it.

 

I used to keep a spreadsheet. Too much work. Now I use fuelly.com which is way better.

 

Interesting...

Although I will probably keep my spreadsheet since I keep a bunch of other things in it also.

 

+1 Fuelly.com

 

An app for fuel mileage logging...please tell me more.

 

The Computer is not very accurate. You should do it the old fashon way with a pencil & paper.

*******************AND**************************** **

Never ever go past two bars left before getting gas. That is if you don't mind running empty.

If I'm on a long vacation trip I get gas every 300 miles weather I need it or not. I can get 400 miles but why take the chance on not finding a quality station. 300 miles is time to pee anyway.

 

It's for android and I'm positive itunes must have one.

it's called "acar"

Tracks mpg, cost, reminds you when to change things (via time or odometer), etc.

Great little app (and it was free).

 

I wonder if maybe the computer is actually pretty accurate in terms of fuel burned but can't account for things like loss from venting. You can lose a lot of fuel through the vapors venting out if you have a habit of topping off.

 

Well, that IS accurate over the time period you're talking about.

Regarding overall accuracy, my OBC is typically within 2-3 mpg of manually calculated values, so I'd say that's OK.

Also, I've gone down to single-digit "miles until empty" several times. No problems.

 

acar - one of the first apps I loaded on my first android phone

Still gonna keep a paper log for a while!

Just wish that we still had 100% gas in this area (TN), the 10% alcohol cut my mileage by 10%

 

Only had the car about a month now (a 2010 R56), but from my early fill ups and calcs., the MPG readout looks consistently optimistic by a bit more than 10%. That is consistent consistent w/ my Audi experience across four different vehicles with similar read outs. Both my Toyota and Chrysler minivans were even more optimistic--more like 15%.

Thus, I have long come to ask any time someone tells me about their great mileage whether they actually computed it from trip meter miles/gallons measured per pump, or they just read it off the optimistic car display. I find many fabulous mileage stories seem tied to a belief those optimistic displays are gospel.

Funny how I have yet to read a story or post where I ever remember someone saying the read out was too low rather than too high... On Audi's it is correctable, in the old days via dip switches; in recent years through quality after market software (VAG-COM/VSCS) that seems far better than anything I have come across from BMW's or Minis in terms of power and user interface. The settings are also documented in Audi repair manuals like from Bentley, etc. I have set that on my various Audi's to where my calculated and actual MPG virtually never varies by more than one or two percent. By contrast, I have never seen documentation/how to's on my Toyota that was always way optimistic.

I did find a Mini post on NAM seeming to say an MPG (actually km/ltr, but same result) correction factor could be applied just based on accessing hidden menus, but from trying it on an R56 where I found very limited functionality (holding down trip computer button while turning on ignition), I'm guessing it may be first gen. specific.

Finally, not clear yet on the miles until empty reading; my Audi experience (and I bet German cars generally) is those are very accurate, since underneath they are looking at calculated fuel in tank from the sensors. Got that sense from the NAM post I found about Mini's in the first gen. vein. As in, it likely runs out of gas if you go more than a few miles after it hits "0." By contrast, I learned I could drive the Chrysler and Toyota about 30 miles "below 0" and still not run out of gas; as in, not very accurate.

 

I just keep a bookmark to fuelly.com on my homescreen on my android phone.

 

acar - sweet!!!! Been looking for something to replace Car Care when I switch from my iPhone to an Android device (though I suppose I could still use the iPhone app).

 

One thing I also noticed (not on mini yet but other cars) is if you drive hard or do more city driving right after fillup, it affects the overall total miles per tank.

This is opposed to filling up and driving on the highway immediatly and noticing a much more optimistic reading.

Yeah, I used to keep an excel spreadsheet on the phone but yeah, ACAR just makes things easier and the reminders are helpful.

 

Quite happy with Gas Cubby on the iPhone. Not free, but worth the price (whatever it was).

 

Today, I filled up for the second time since taking delivery and made some calculations:

I drove 291.7 miles up until todays fill up.
I filled up with 11.94 gallons.

The math comes out to just under 27mpg which would indicate the computer is correct.

I drive a pretty even mix of highway/city and have not pushed the engine hard since it's still breaking in (600+ miles at this point).

I have noticed fuel consumption is at its worst when the engine hasn't reached normal operating temp. My commute is 3 miles each way to and from work so it never really gets to warm up fully.

But still for a new car doesn't this fuel mileage seem a bit low?

 

291.7 miles divided by 11.94 gallons comes up to 24.4 mpg. How are you getting just under 27?

If you are only driving to and from work and it is a short drive, I'd suggest you hit the road on the weekend and get in some good motoring. You don't have to push it hard or anything per the break-in guidelines (though there is a line of thought out there that recommends that). But I would do something to let the motor get fully up to normal operating temperature and keep it there for a while. The short, three-mile trips is effectively severe duty and I would think you should mix in some normal duty during the break-in.

Will have to think some on how the short trips may be throwing the computer off when it tries to do its calculations. But first, probably need to get the manual calculations straight.

 

Does it really matter what the computer says? EVERY car comes with a fuel gauge, that is what you should pay attention to, and if you like to drive around on EMPTY you shulda bought a VESPA.

 

Sorry I typed the numbers wrong. They should be: 321.7mi/11.94gal=26.9mpg.

 

Not sure how driving around on empty (which I dont) or buying a Vespa (which I wont) has anything to with my OP but my point is that the MPG I'm getting is way off the EPA numbers and I'm concerned something isn't right.