How big is the fuel tank (again)?

Posted on by Ian C.

A few months ago I wondered just how big the gas tank was in GBMINI#3; the specs say 13.2 (US) gallons …
Yesterday during my day out in Boston, I got the distance-to-empty down below 5 miles, and was shocked when I filled the car:

More than 10% over the claimed capacity! I never got anywhere near this much in GBMINI#2, and I ran it down to about 0 miles to empty a few times …

Is the ’05 fuel tank bigger? Is the MCS auto fuel tank bigger? We need an official answer to this mystery! 😉

20 thoughts on “How big is the fuel tank (again)?”

  1. That time I got the OBC to get to 0 miles remaining, I only was able to put in 12.9 gallons. My 0 probably doesn’t mean 0…

  5. Wish I was paying $2.65 for gas 😦

    That would seem to be WAY over what the manual says. Do you trust the accuracy of the pumps? ’cause over a gallon more you would think that would be listed someplace, right?

  8. 2.65??? wow. Saw a gas station out in El Centro yesterday with el premo unl for $3.21 but I managed to find $2.95. Bargain!

  10. I paid $3.17/gallon for Premium in Chicago on Friday. Wish I had gotten gas the day before as the same gas station was $3.09/gallon. Oh what a difference a day makes. I DID break $40.00 filling up. Never thought that would happen in a MINI. Also, I’ve put more than 13.2 gallons in the car before and it was not down to zero. Close, but not there. I drive an ’05 as well.

  11. Looking at my mileage spreadsheet, the most I’ve put in has been 13.6 gallons… I’ve got an April ’05 build MCS. How much did you pour onto the concrete? 😉

    I would definitely question the pump.

    Are you tracking the OBC vs. calculated (actual) consumption? The biggest discrepancy I’ve seen between the two has been the OBC reading 1.9 MPG higher than the calculated amount, but it’s usually within 1.2 MPG. Might be interesting to see what yours was to see who’s right. 🙂

  12. I have put over 14 several times, though usually 14.1 or 14.2. I have an 04 without the computer so I rely on forgetting to get gas and lots of short trips to get it that low. 😉

  13. The most I’ve ever pumped into my 03 MCS is just over 13 gal.

    I say don’t trust the pump. The reason they have to be checked is because they can be wrong. Reports show that faulty pumps can be off as much as 7 oz. per gallon. This is rare and when discivered they’ll be shut down and maybe fined but it happens.

    The laws that govern the amount of fuel dispensed allow for plus or minus .5 percent. That doesn’t seem that would make much difference but could account for about 2 cents per gallon loss (at $3/gal). (That won’t account for your results above, though.)

    The reason for allowing a .5 percent variation is temperature. Gasoline expands at higher temperatures. A pump can be calibrated to dispense exactly a gallon of fuel at 80 degrees but a 10 degree increase in temp. can affect that amount by 2 oz. per gallon because of expansion. You’re still getting a gallon (volume) of fuel but there is less energy inthat gallon. There is “x” amount of energy in a gallon of fuel at 80 degrees. If the temperature goes up and the fuel expands, a one gallon volume has less energy and therefore fewer MPG. Because of this, try to fill up at cooler times of the day to get the best value/amount of fuel.

    Yes, my degree is in chemistry (geek check) although it’s not what I do. : )

  14. So, I dumped in 13.968 last fillup and if I remembered, I think I had about 10-15 miles to go. I figure the mileage computer MUST be set up to be conservative, so I too thought the tank must be bigger than advertised. I wonder if it’s a combination of bigger & optimistic pump?

  16. Doesn’t the manual also say that we have a two gallon reserve? Or was that from dreaming about my MINI before it got delievered?

  17. 1. The tank volume in your manual doesn’t count the space in the filler neck… just the volume that the tank alone could hold on a flat surface. Having a filler neck also allows ALL of the tank to be filled, gaining even more volume. This could very well account for the greater volume.

    2. I love the combination of chemistry with MINIs, but throw in some geology (or construction experience). Once you get below the frost line (which almost every underground fuel tank must be), the temperature doesn’t vary more than 8-10 degrees throughout the entire year… probably not enough to effect a substantial change in volume unless a phase conversion was in order (liquid to vapor).

    3. The staion may have tweaked their pumps to measure more than dispensed, but I thought that those things were under a state inspection seal and were inspected several times a year.

    4. Love the site. Thanks for sharing your ‘MINI life’ with us.

  18. I’m trying to figure out the whole “miles left” bit… how do yo get to that? (probably should consult the manual) I bet mine doesn’t have that option, sounds like one of the things you’d have to have the Chrono pack for.. ???

  19. Derek,
    It is the “OBC” option and gives more displays available on the place where temperature & digital speed is shown.

  20. UP
    Apparently that pump filled very close to the top because that fills MPG was low, but the next fill was high – and the average of the two fills (26.2mpg) is typical.

    So yes, you can get 14-1/2 US gallons in a MINI!

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