Just to clarify the confusion Curtis, US gallons are not the same as Imperial/UK gallons. A US gallon is smaller. It's 83% of the Imperial gallon.
Robin is correct that 11 miles to the litre is 50mpg, on this side of the Atlantic.
All of our pumps are only showing litres for dispensing fuel so we tend to think in terms of the miles we get for a litre. 10 to 11 miles/litre is about average for most big engined bikes and petrol engined cars under 1.5 litres, but this can vary depending on traffic conditions etc.
Sorry, did not correct for the imperial gallon. My bad. To boot, I have been on editorial boards for scientific journals and review for about 24 different journals. Must have been a senior moment. To be honest, the one dragging their feet to convert to the metric system is the U.S. One of my favorite items is a jam jar that is supposed to be one pound, and I swear, it read 453 KG on the label! I want to know how they got about a half ton of blackberry jam into that jar. That was SOME trick.
Of course, this is great for the manufacturer of tools. We end up with a set of SAE and a set of metrics. 50 mpg is good any day of the week. I am getting about 45 routinely on my SE A1 Thunderbird. That is not bad for an 812 pound machine.