I really don't understand the disparity in mileage we all have. We do some seem to do so much better than others?

I live in South Florida, flat terrain, usually warm to hot climate, etc. Assertive driving style at times, but usually relatively conservative. Slightly aggressive off the green light.

2005 Limited Coupe, AutoStick. Other than K&N air filters, stock all the way around.

I have averaged about 20 MPG with each new tank full almost the entire time I've owned my XF. This is both in the summer using the AC a lot, and in the winter when I rarely use it all. I almost never make it to 300 miles on a full tank driving exclusively around town.

On those few occasions when I've had to drive about 100-150 miles round-trip on the highways, along with the usual around town driving for the remainder of the tank... 23 MPG.

I almost wish I could just blow a full tank of gas on a LONG highway drive just to see what mileage I get under the best of circumstances, but it seems like a foolish way to spend $50 in gas and 4+ hours driving nowhere. And you know I'm gonna be going 80 mph the whole way, leaving me an unnecessary potential blue light candidate all the while.

I'll be honest, I expected (hoped for) better.