Yes quite. That's why it's important for a single unit of measurement.
Imagine how it would be if some fuel stations priced by the litre whilst
others priced by the gallon. How easy would it be to compare prices.
The only issue with that is the way people gauge economy.
I've never heard anyone refer to anything other than MPG for this.
If your car is of the older type that don't show an MPG display then you'd
have to fill up - note the litreage make the conversion and then find out if
the MPG is what it says it should be. I found out that my wife's old fiesta
was under-economic with that - but then it has got over 100k* on the clock!
(* In the UK thousands of clocked miles tends to be known as 'k' - I'm not
sure if this happens in the US)
