I have about 850 miles a 2012 MT sport and I have averaged about 34MPG. 70% Hwy. The meter seems to be pretty dead on.

 

I was going to start a new thread but found this with the search button. Checked the meter on the last couple of fill ups and mine seems to be accurate, like under +/- 1 mpg accurate.

 

I have a 2008 1.4 manual and I get 55 to 58 mpg easy. On LPG it does slightly less say 50 to 54 mpg but LPG is half the price.
Does anyone know if the fuel tank has a float to work out how much petrol is in the tank? I guess it doesn't it works it out with the computer only as mine drops even though I use LPG and not petrol. It can show empty even though its 3/4s full of petrol.

 

Yes, it does, but this isn't used in the MPG calculation (don't they do L/100KM in merry ol' instead of miles per imperial gallon?). For fuel consumption it uses data from the fuel injection along with how fast/far you're travelling to come up with a number. It's pretty accurate (+/- 3%). I'm guessing this works for either petrol or liquid petroleum gas (LPG).

we yanks don't have dual fuel Fits so I'm not sure how the tank level function works for you. Was that available from the factory?

 

No I had it fitted afterwards. There is s separate gauge for the LPG .The fuel gauge for the petrol just goes down as I do the miles then goes mad when it says I have no petrol. It then slowly goes up over the day. Its really strange? It can't be working off a float ?

 

yes, it has a float (fuel level sender) to determine remaining fuel and display this on the fuel level gauge. But this doesn't affect MPG calculation (fuel level doesn't matter); that's purely on fuel used as measured by the injection. If the gauges (fuel level or mpg) are acting wonky, I'd visit the bloke that did your LPG installation. Ha, I said "bloke" (we don't use that word any more than we say petrol).

 

No its got to be something funny with the computer and the fuel gauge as when I fill up say £10 of petrol because that's all that will fit in (£48.00 normally to fill it ) It knows its full as the gauge goes up to the top.The guys who fitted it didn't touch the petrol tank, they are not linked at all.

 

I use the fuel buddy app to record my fillups and I also reset my trip odo and record my dashboard average mpg over the same tank. I downloaded it all into a spreadsheet a few weeks ago. Over 29 fillups the dash average mpg read an average of 1.4% high. Though some it read higher and some it was actually on the low side.

 

Exactly what i was wondering. I wonder how "big" the memory buffer is for the MPG data. Like if the MPG samples are last 200miles worth or xxxx thousands until you reset? Reason why i ask is because there is a huge difference in shown MPG like say you drove like a Jeff Gordon the first 200 miles of the tank but went Prius style towards the end vs driving like a Prius driver at the beginning and then like a Jeff Gordon towards the end. If the memory buffer for the avg is really until reset then it should equal the same mpg per tank assuming the situation is the same either direction but its not.

If you start to drive slow towards the end of the tank the mpg will rise to a avg of like 38.5mpg yet if i were to drive like a bad out of hell towards the end it will drop from 40.8mpg to like 33mpg.

Here is my awesome mpg across a super humid hot city traffic, those intake temps are bazzar, usually around 87-90degrees.