In the European Union, passenger vehicles are commonly tested using two drive cycles, and corresponding fuel economies are reported as 'urban' and 'extra-urban', in litres per 100 km and (in the UK) in miles per imperial gallon.
In the European Union advertising has to show Carbon dioxide (CO2)-emission and fuel consumption data in a clear way as described in the UK Statutory Instrument 2004 No 1661.
Want a good economic car?? Buy one from Europe, by law they have to do at least 35mpg.