The Nissan Leaf electric car has received a “mile per gallon equivalent” rating from the Environmental Protection Agency (EPA), so it can officially go on sale when inventory hits dealerships. The EPA has rated the Leaf at 99 miles per gallon equivalent (MPGe), based on a city economy of 106 MPGe and a highway economy of 92 MPGe. Also factoring into the efficiency equation is a Level 2 charge time of seven hours and a tested full charge range of 73 miles. Nissan claims a range between 47 miles (absolute worst case scenario) and 138 miles (absolute best case scenario), and the EPA estimate of 73 miles is based on a five cycle test using a mix of driving conditions and climate controls.
For the purpose of rating EVs, the EPA uses 33.7 kW-hrs as the equivalent of a single gallon of gas. The Leaf uses a 24 kW-hr battery pack, which yields an EPA estimated range of 73 miles. If the Leaf had a 33.7 kW-hr battery pack (or 40% more capacity), the EPA tells us it could go 99 miles, hence the rating. There’s got to be other variables in the equation, since I ran the numbers half a dozen times and I always come back with an estimated MPGe of 102.2 miles. Math wizards, help me out here.
This should make rating the Chevy Volt plenty confusing, which explains the delay on its EPA fuel economy sticker. On the one hand, you’ve got a 16 kW-hr battery, which yields a range to be determined by the EPA. On top of that, you’ve got a gasoline powered generator which yields roughly 300 miles of range from 9 gallons of gas. Will the Volt get two separate ratings, one for MPGe and one for MPG? Will the EPA average the two ratings, even though the Volt is designed primarily as an electric commuter car, but with extended range capabilities? I can’t wait to see the outcome of this one, and I have a feeling that Chevy won’t be pleased with whatever the EPA’s numbers work out to be.