In Canada we use the British gallon which is 4.535 litres. The American gallon is defined as 3.786 litres. Obviously, the Canadian gallon is the larger (ratio of 1.2 as mentioned previously).
Here is a site that speaks to the Canadian gallon.
http://www.statman.info/conversions/...nsumption.html
I put in my 12.2 L/100km and choose 'miles per gallon (U.K.)' for a nice 23mpg. I have never reset my numbers (am now at 2202 km) and it's mostly city driving. I'd say that's pretty close on the window sticker.