l/100km -- mpg

[Mario149]

Apologies in advance for the dull question, but does anyone know how to change the fuel consumption units to mpg from l/100km on the central display on a Mitsubishi Colt CZ1? I've got one as a hire car for my work commute and as much as I fiddle with menu buttons etc, I just can't seem to change it, and it's annoying me far more than it should!

TIA