I started a thread here about 3 months ago and a considerable number of people reported XJ highway mileage as high as 25 mpgs. In fact I bought I bought one that was getting 24 mpg before the head gasket went out. Unless you live in a city with no lights, not stop signs and only downhill trips all the time I suspect the scanner is off, but where is it, the scanner, getting its gasoline volume reading, flow rate data from? The scanner has no flow rate sensor in it, right? So it is estimating that rate or getting a reported estimate from the jeep computer based on injector open time and fuel pump pressure right? Volume does vary considerably with temperature of the fuel!!!!! The computer may be using a default gas temperature assumption.
I would suspect there is an error in there somewhere. The cold air in Canada might be helping the efficiency some. I have seen believable reports as high as 25 mpg highway.
