No MPGs for EVs

Jeremy Anwyl, the CEO of Edmunds.com, a consumer auto site that also offers industry analysis, has suggested that the EPA revise how it measures fuel-efficiency for cars and trucks. With new electric vehicles coming to market, he argues that rather than develop complex formulas for translating EV MPGs into gas equivalents, the agency should “start over”:

“Trying to convert various forms of energy to a standard is missing the point. Stepping back from the issue, it should be clear that consumers have used the existing MPG ratings primarily to get a sense of the relative cost of operating a vehicle on a day-to-day basis. MPG is not a direct measure of costs, but as long as fuel quantities are measured in gallons, MPG provides a relative guide. A vehicle that consumed more gallons costs more to operate. Simple enough.

“With energy equivalents, the picture is anything but simple. Some of the draft data I have seen can easily cause consumers to draw erroneous conclusions. For example, a new Toyota Prius has a combined 50 MPG. GM is reporting that its new Chevy Volt will possibly be rated at 230 MPG. From this we could reasonably assume the Prius is more than four times more costly to operate than the Volt. But we would be wrong.”

At issue here is whether the Volt, which can run on its electric motor for 40 miles before switching to a small gas-motor to generate additional electricity, would actually consume fuel at anything resembling the rate a Prius does (the Prius burns gas when it’s driven at speeds higher than about 20-30 mph). That depends on consumer driving patterns. If Volt engineers are correct and most drivers only cover around 40 miles per day, then most of the time the Volt will be operating in all-electric mode and never need to tap into its gas reserve. Refueling will consist of recharging overnight, or at fast-charging stations. Obviously, many drivers will burn some gas. But theoretically, the Volt could get an infinite number of MPGs.

And that needs to be taken into account as a market differentiator, especially if series hybrids are to distinguish themselves from parallel hybrids of the Prius type and full-on EVs, such as a Nissan Leaf. Basically, the Volt is an EV with an insurance policy, X gallons of gas (depending on how many additional miles the diver thinks he or she might need to go). Placing the Volt in competition with, say, the Prius, on monthly operating costs, as Edmunds suggests, is actually unfair because it makes too many assumptions about how Volt owners will use their cars.

It’s not that Anwyl isn’t on to something, it’s just that in an effort to provide a tidy picture for the consumer and insist that the EPA fairly compare EVs, hybrids, and regular gas-powered cars, he’s overlooking how potential Volt owners will behave. They’re likely to curtail their driving, or consolidate it, in an effort to stay in all-electric mode, at least initially. They’ll probably also limit the amount of gas they carry around. But even if they carry a full-load of gas around, by my estimations they’ll need to fill up less than six times. Obviously, it’s not hard to envision Volt owners who visit the gas station two or three times per year, and that’s an economic advantage to ownership that should be represented on the car’s window sticker. In a sense, it’s more convincing than claiming that the Volt will get 230 mpg.