We do have something of a mix of units.
We buy oil and fuel in litres but reckon consumption in MPG. Why - because distances and speed limits are still in miles.
Don't you guys in the US ever go metric or you'll end up trying to figure consumption in L/100 Km which makes no sense to me at all.
In Canada that's what we officially use. I basically just memorized rough conversion because US MPG is what most people casually use. 7.9 L/100km is about 30 US mpg.