After yesterday's 99 miles per gallon (equivalent) EPA rating for the Nissan Leaf, General Motors had to be eager to get the numbers for the Chevy Volt from the government – if for no other reason than because these efficiency stickers are the last thing holding up deliveries of the first production vehicles.

Today, GM shared the official numbers with the world, and they range from 37 miles per gallon to 93 mpge (equivalent) combined to 60 mpg "composite." Sixty mpg composite is a "combined, combined" number, and will be completely different for everyone. You might want to think of it as a lifetime figure, since it accounts for both electricity and gasoline consumed. Oh, and it's also best in class for compact cars. The Volt's official electric-only range will be 35 miles, but GM, like Nissan, has been giving a range recently of 25-50 miles. The Volt now has an official total range of 379 miles, with 344 miles of that being extended range (i.e., gas) driving. As Tony DiSalle, Chevrolet product marketing director, said, "If you try to boil it down to a single number, it gets quite difficult."

Doug Parks, Chevrolet Volt Global Vehicle Line Executive, said he is "quite pleased" with the numbers and understands that it is a complicated story to tell. GM and the EPA worked together to come up with this label to figure in all of the different modes that impact the vehicle's efficiency. We've heard that the 2011 Volt will have a temporary EPA label, but Parks told us that what you see above will likely be what we see in next year, saying "Our intent was not to do something that was a one-year deal. Our hope is that this is very similar to the path that everyone will go down in the future. We tried to make the label look as similar as it can to next year."

So, what about that "230 mpg" GM touted last year. Well, that was a different way to calculate things. "230 by itself was never intended to be a composite number," Parks said.

[Source: General Motors]