We missed a bug in the 1.3 release - we special case GB so that information is shown in metric, even though you measure in MPG.  That's wrong on our part! We'll fix that bug in the next update.  We'll still read locale information from your phone automatically - (we'll let you override that when we introduce a settings screen (soon)!  We'll also introduce functionality to let you switch back and forth between miles and kilometers and liters and gallons (it's really simple math - just a matter of keeping the details straight)

But we're sorry for now - UK customers won't get much use out of the current version.  Please stay tuned!