Yep, and those two gallons aren't even remotely close. It's the most annoying thing on car forums, because someone will always say "oh my car gets 30mpg but everyone here says they are getting 40mpg!"
Like, yes, because you haven't established whether they mean US MPG or Imperial MPG.
YES! I always assume ( and very stupid of me ) that it was some regulation with cars and the way they drive between US and UK making some difference in MPG. I never knew the G in mpg was different!
This is one of the illustration with online or even real world discussions where we argue pass each other under the wrong basic assumption.
Like, yes, because you haven't established whether they mean US MPG or Imperial MPG.