I always record mpg of all my cars, full to full tank. I like to keep stats and total cost. I don't try to drive economically, it's forced on me with speed cameras and road works with 50mph limits. I don't use eco mode or start/stop. There's no need to drive like crazy all the time. I can have some fun, but there are still boring commutes on motorways. I would never get the same mpg if I was living in city in UK or somewhere in Germany with higher speed limits or lack of limits.
In past, I took my cars to Germany purely for fuel burning exercise but now it's not an option. My personal favourite is burning tank of petrol ( from full to reserve - 58l) in 1h 52m, with average speed of 106mph - 171km/h.