Since 1 January 2001 a fuel consumption label has been placed on the windscreens of all new vehicles up to 3.5 tonne gross vehicle mass. The removable label shows the fuel consumption (urban, extra-urban and combined) of the car in litres/100km and the CO2 emissions in g/km based on a standard test. The label enables new car buyers to compare vehicles on a common basis. As of 1 March 2011, a fuel consumption label has also been attached to the windscreens of all new electric and externally chargeable ("plug-in") hybrid electric vehicles. This label shows the vehicle's energy consumption in Watt hours/km, expected range when fully charged, fuel consumption in litres/100km and CO2 emissions in g/km based on a standard test. While the label alerts consumers to possible CO2 emissions from recharging, it does not attempt to quantify those emissions on the label, as this will depend on how the electricity is generated. Consumers are encouraged to visit the Green Vehicle Guide website to estimate the vehicle's recharge emissions.