we have had the metric L/100km system in aus for so long we are used to a smaller number in better.
with the MPG system a higher number is better, it took us years to get used to it,
the younger the person the less they will relate to MPG, i went through both systems during my school years, i started school with imperial and finished in metric, so i had to learn both, if i ask my 20+ y/o stepsons to explane MPG