A British couple recently took a stock Jeep Patriot and Compass on a trip across Europe for the "Jeep Fuel Economy Challenge". Their goal was to see how far they could make it on a single tank of fuel.
As far as I can tell, both cars were stock, and the test seems to be well documented. In the end, they were able to go over 1,000km from London to Poland on a single tank! In the end, the Patriot made over 67MPG while the Compass made over 66MPG.
This is pretty amazing, even if they were coasting half the time...