Miles per Gallon: Soon to Be Useless

With any luck, we'll be moving on from these gas-only automobiles in the coming years and that means we'll have to find some measure for a car's efficiency besides miles per gallon. In fact, the petronormativity of the mpg standard is already causing confusion. The Chevy Volt was boasting 230 mpg and the electric Nissan Leaf claimed 367 mpg. Those numbers are hard to interpret because neither car runs exclusively on gas. And how do you even talk about the efficiency of a hydrogen car?It looks like the Environmental Protection Agency is working on a solution:An Israeli firm last week urged the EPA to come up with a three-pronged number that would tell people how much electricity a car uses when it's fully charged, how much electricity it takes to charge the car and how much gas the car uses when it's out of juice. On Monday, the National Renewable Energy Laboratory, a government agency, said they believe the new figure will give buyers two pieces of data, although what those two numbers are hasn't yet been decided. With both the Volt and Leaf due to go on the market late next year, the rejiggered formulas could have a big impact on sales.It seems to me there are two things a car's efficiency figure should tell you: How expensive fueling the car will be and how bad operating the car is for the environment. As we move to plug-ins and electric cars we can get the first piece of information by measuring how many miles you get from each kilowatt-hour of charging time. For the latter, though, it depends on where the electricity comes from in the first place. If you have a less efficient electric car but only charge it at a solar powered charging station, that's way better for the planet than a high-efficiency electric car that you charge using electricity that's generated from coal. So it's complicated.