EPA should not list combined ratings for upcoming electric vehicles

I’ve been reading up on the Chevy Volt, Nissan Leaf, and other electric cars. It seems the EPA is trying to figure out how to rate such cars for their efficiency. Unfortunately, perhaps due to the desire of automakers wishing to impress consumers with big numbers that relate to current labels, they’re leaning towards relating the efficiency of electric vehicles in miles per gallon or combined ratings that try to reduce the efficiencies or range of multiple methods of energy storage into single numbers that are difficult to entangle into real information.

This next paragraph is going to sound like a grade-school mathematics word problem, but bear with me. The Chevy Volt has an electric motor and a battery. When the battery is depleted, a gas generator kicks in to power the electric motor and extend the range. Chevy says their battery will power 40-miles of driving. So a person who drives less than 40-miles a day might only use gas on rare occasions. So for that person, a displayed rating of 40-miles-per-charge would be the most useful rating. For a person who regularly takes a 400 mile drive from Los Angeles to San Francisco, 90% of their drive would be powered by the generator. For them, the number they’d need to see would be how may miles-per-gallon they’d get. The EPA’s current label design would fail to communicate anything of use to either the people in these examples.

Instead, they’re doing some kind of weird combined rating that relates to kilowatt-hours used per 100 miles of travel. This awards the Chevy Volt a rating of 236 mpg. Sounds impressive, but that’s not a number that relates to one’s experience of using the car. I typically drive less than 100 miles a week. If I were in the market for an electric vehicle, I’d use zero gallons of gas most weeks. ∞ mpg?

 Files Mini-E-Sticker

Here’s the EPA draft label, for the BMW Mini-E. That car can travel 156 miles on a single charge. It’d be much more useful if that range were just printed on the label, rather than “33kW-hr/100 miles (equivalent to 102 MPG)”.

EPA, if you’re listening, please label electric cars as follows. Show the distance the car can go on a single battery charge. If the vehicle switches to another fuel when the battery is depleted, then separately show the distance it can go on that fuel along with the size of that fuel tank. Nice and simple. 2 big numbers (distance ranges), one small number (size of secondary fuel tank). The car manufacturers wouldn’t be able to tout awesomely high miles-per-gallon ratings, but it’d be a more honest and intelligible way to rate methods of propulsion that use fuel not measured by the gallon.


del.icio.us:EPA should not list combined ratings for upcoming electric vehicles digg:EPA should not list combined ratings for upcoming electric vehicles spurl:EPA should not list combined ratings for upcoming electric vehicles wists:EPA should not list combined ratings for upcoming electric vehicles simpy:EPA should not list combined ratings for upcoming electric vehicles newsvine:EPA should not list combined ratings for upcoming electric vehicles blinklist:EPA should not list combined ratings for upcoming electric vehicles furl:EPA should not list combined ratings for upcoming electric vehicles reddit:EPA should not list combined ratings for upcoming electric vehicles fark:EPA should not list combined ratings for upcoming electric vehicles blogmarks:EPA should not list combined ratings for upcoming electric vehicles Y!:EPA should not list combined ratings for upcoming electric vehicles smarking:EPA should not list combined ratings for upcoming electric vehicles magnolia:EPA should not list combined ratings for upcoming electric vehicles segnalo:EPA should not list combined ratings for upcoming electric vehicles gifttagging:EPA should not list combined ratings for upcoming electric vehicles