These days, it seems you can’t open a newspaper, listen to a radio, or read a blog without seeing the number “230” and the words “Chevy Volt.” When I typed “230” into Google a few minutes ago, three of the first four hits were about the Volt. At my local gym this morning, three people asked about 230 and the Volt.
Could it really be possible, they ask, for the Chevy Volt to get 230 mpg?
Before we answer the question, however, let’s back up and explain the significance of the number 230 for those who missed it. Two weeks ago, General Motors CEO Fritz Henderson announced that, using a draft EPA methodology as a measure, GM expected the Chevy Volt to achieve city fuel economy of 230 mpg. The story was picked up by virtually every news outlet in the country, leaving a lot of Americans scratching their heads, since most know that the Chevy Volt is a plug-in hybrid vehicle that runs on electricity.
As if that wasn’t confusing enough, Nissan announced days later that its forthcoming battery-powered Nissan Leaf will get 367 mpg.
So what’s it all mean? The short answer is no one knows, since both companies based their calculations on a draft methodology that hasn’t been officially released to the public. Worse, the information vacuum has spawned a multitude of Internet myths, the worst of those being that GM based its calculations on a 51.1-mile driving cycle, in which battery power was used for 40 miles and gasoline for only 11.1. GM says that’s absolutely untrue.
What we do know about the numbers is that they are miles per gallon equivalents (called MPGe). Nissan says they calculated their 367-mpg in a very simple fashion. A spokesman for the company told us that the Leaf consumes 0.223 kW-hrs/mile. By dividing that number into 82.048 kW-hrs/gallon (a gallon-of-gasoline equivalency number they got from the EPA), they reached a conclusion of 367 mpg.
GM’s calculation, however, is a harder one. But because the Volt uses rechargeable batteries and gasoline, and since the EPA isn’t explaining its methodology, it’s hard to say how meaningful the numbers are.
Some experts say that the growing confusion is a sign that a transparent universal standard for fuel efficiency is needed. One such universal standard, being promoted by the Progressive Automotive X Prize Foundation, calls for all burned energy to be expressed in BTUs, and then converted to miles per gallon. As a result, MPGe would be calculated this way:
MPGe = Miles driven / [(energy burned in BTUs)/(116,090 BTU per gal of gas)]
Using this method, or a method like it, there could be one standard way of expressing the amount of energy burned, no matter the fuel. Moreover, consumers could compare alternate-fuel vehicles, or multi-fuel vehicles, to the fuel efficiency of their current gasoline-burning cars.
I suspect the EPA may be using a similar method, but since we can’t see it, we don’t know for sure.
The bottom line is that the auto industry needs an understandable fuel efficiency standard, and they need it soon. Otherwise, the confusion we’re seeing today among consumers and on the Internet is bound to get worse.
“We love to see progress,” notes John Shore, senior advisor to the Automotive X Prize Foundation. “But right now, beyond saying these cars are getting good fuel efficiency, we don’t know how meaningful it all is.”