The rating is given as an average between city driving and highway driving, where it achieved 2.55L/100km in the city and 2.2L/100km on the highway. The car was also rated at the maximum end of the scale in range, and was rated at achieving 73 miles - 117km.
Even though the car is an electric vehicle, the EPA is able to determine how much energy the car uses following a formula. The formula says 33.7 kWhs are equivalent to one gallon (3.78L) of fuel energy. The EPA was then able to calculate that the Leaf is able to travel 3.4 miles (5.47km) per kWh. Because the Nissan Leaf uses a 24 kWh battery pack and can achieve 73 miles, if it had a 33.7kWh battery then it is possible it could go 99 miles, hence the rating. This battery can then be recharged, also quoted on the sticker, in around seven hours using a 240V socket.
Other areas where the car rated highly in favour of the environment was greenhouse emissions where it scored 'best' with zero greenhouse gases, and was rated 10 in 'other air pollutants', also the maximum rating. Annual cost expectancies are also given on the sticker where the EPA says $561 should just about cover it.
It's the first of such stickers to be applied to an EV. The Chevrolet Volt is yet to be rated.