230 MPG? Really?

Chevrolet is putting out that the Volt will get an EPA rating of 230 MPG. That begs the question - how in the world do you determine something like that? Well, the answers are out there, but they are not easy to find.

Autoblog digs up some facts:

According to a commenter on TTAC.com, the EPA would first drive a PHEV with a full charge until it reaches a charge-sustaining mode, after which it completes a normal cycle of 11 miles. The Volt, therefore, would presumably go 40 miles before activating charge-sustaining mode, and then travel another 11 miles for a total of 51 miles. Thus, GM can claim the Volt will achieve 230 mpg based on 51 miles of driving during which only .22 gallons of fuel would be used. Likewise, if we know the Volt would use .22 gallons of fuel while traveling 11 miles in charge-sustaining mode, we can calculate that it would achieve 50 mpg while traveling with the generator on.

That helps, but it isn't enough. Theoretically, if you drove <40 miles every day, and charged your Volt every night, then you would never use any gas. That kind of makes the whole Miles Per Gallon thing superfluous. However, if you are on a long trip and are going to get 40 miles of battery only travel before the engine kicks in for the rest of the trip then it is not going to be that much different than a regular car. How can you take into account both extremes?

It seems to me that we need to move towards some kind of energy use measurement that would take into account all forms of propulsion be it electrical, hydrogen, gasoline, cold fusion or whatever. We just have to get used to talking in kW per Mile or Miles per kW or something similar. The hybrids are still going to cause problems because of their multiple sources of power, but I'm sure the EPA can work out the details. Then the question becomes whether or not the public can make the switch, and this in a country where we can't even adopt the metric system.

On another note it will be interesting to see what mileage the EPA actually puts on the Volt. Of course, when you consider that Chevy is now owned by the very entity that will be determining the rating, the question is probably moot.