l/100km calculation shown after posting is incorrect.
 

Here is a sample posting:

MPG: 46.0
L/100km: 5.1
Miles: 510.0
Litres: 50.450
Price: £1.199/Litre
Total: £60.490

46.0 MPG (Imp) is not 5.1l/100km but should be 6.14l/100km.

I have seen similar errors with other (all?) postings.

Where are you fueling up? The mobile site at m.fuelly.com or the standard web site? And do you have UK units selected in the upper left corner of the page?

Google says it's right.

The differance is US gallons vs. British or Imperial gallon measurment. 50.450 litres per 510.0 miles is 5.1 litres per 100 km, but the correction should be an increase from 46.0 MPG (US) to 55.0 MPG (British).

Thanks rob01, I'm guessing jostlehim doesn't have UK units set for the site. The default is US units.

Actually, I do have UK units set, and more to the point I am entering the values in litres, not gallons. 510 miles is c. 820 km. 50.45 litres divided by 8.2 gives 6.15 litres/100km.

Since I am entering the volume of fuel in litres, it should eliminate the whole Imperial/UK gallon issue. The mpg is correct for the UK values. My overall l/100 km values are correct. But each time I fuel, the reading for that fill-up given to check your figures is wrong by 1l/100km.

I'm entering the fuel-ups on the standard site.