Use this useful tool to convert weight choosing one of the 11 units of measurment included in this app, that are:

Metric Units:
litre per 100 kilometers, litre per kilometer, gallon per 100 kilometers, gallon per kilometer, kilometer per litre, kilometer per gallon

U.S. and imperial units:
mile per gallon, mile per gallon

CO2 emissions:
gram of CO2 per km (Diesel), gram of CO2 per km (Gasoline), gram of CO2 per km (Autogas)