Some French journalists just posted a video of a fuel economy test of the 1.2L, 5-speed car (Mirage is called "Space Star" in France and other Euro countries).
Notable: they stuck to posted speed limits, and 45% of the round trip was on freeways at
81 mph / 130 km/h. Total trip length was 249 miles (400 km).
Another 45% was secondary roads, and 10% was urban driving.
They filled to the brim at the same station before & after, using the same pump, same fuel (E10), and still managed
44.6 mpg (US) / 5.28 L/100 km.
Video of the adventure below. I've posted English translation of the subtitled info here:
Economy run in south of France, 1.2 5MT: 5.3 LKH (44.6 mpg US) up to 130 kph (81 mph)