TRAVERSE CITY, MI – General Motors Co. remains months away from receiving a fuel-economy rating from the U.S. government for its Chevrolet Volt extended-range electric vehicle, the auto maker’s top electrification executive says.

Larry Nitz, executive director-Hybrid and Electric Powertrain Engineering at GM, expects the rating to come by the end of this year.

GM launches the Volt in the fourth quarter and it cannot go on sale without the rating, but the EREV breaks entirely new ground when it comes to determining mileage.

“We don’t have a label,” he tells journalists after a forum on advanced powertrains at the annual CAR Management Briefing Seminars here. “There is no policy or procedure for the label, and that’s a challenge.”

Nitz says the auto maker continues to work with the Environmental Protection Agency, which sets the fuel-economy ratings.

“Don’t have it today,” he adds. “But hopefully we have it very soon. We’re going to need it in a couple months because we are going to be launching in November.”

Nitz says the EPA is “not close to finalizing the label. They say the end of the year, but that’s the general label. What they’ve agreed to is to work with us on a specific label.”

Auto makers and the Society of Automotive Engineers have been working on a standard for fuel-economy ratings on EVs, but the numbers must include factors such as driver aggressiveness, ambient temperature, HVAC system use and charging frequency.

However, the Volt throws another curveball. In addition to its 40-mile (64-km) all-electric range on battery power, an internal-combustion engine will engage to provide another 300 miles (483 km) of driving.

Last year, GM launched a national marketing campaign touting 230 mpg (1.0 L/100 km) in the city cycle for the Volt. It later backed off the EPA-approved number under criticism from environmentalists and parts of the engineering community.

“But the good news is we’re getting 40 miles,” Nitz says of the Volt’s confirmed average range on electrical power.

The Volt arguably ranks as the most important new-vehicle launch in GM’s history, an introduction that will be watched closely after the auto maker’s taxpayer-funded bankruptcy last year.

Nitz also says GM continues to believe next-generation cellulosic ethanol represents the best near-term solution for diversifying the U.S. away from imported oil. Some 5.5 million flex-fuel vehicles are on the road today, and auto makers continue to build more.

GM invested in a pair of cellulosic ethanol start-up companies planning to manufacture the biofuel from any number of sources, which eliminates the food-vs.-fuel controversy that comes with corn-based ethanol.

The two ethanol companies continue building demonstration refineries they will use to show investors the potential for the technology.

“That Gen 2 ethanol is where we’re making some bets,” Nitz says. “It certainly is an important part of the ethanol equation. If you bring on the cellulosic ethanol, it opens a whole different set of feedstocks.”

Nitz admits the infrastructure for current-generation ethanol, or E85, remains modest after years of trying to make more pumps available. Pricing also remains unstable outside the Midwest.

“We need policy that supports it and gets it to peoples’ cars,” he says.

Also in his presentation, Nitz confirms plans to introduce GM’s second-generation belt-alternator-starter technology next year on one of the auto maker’s passenger cars with a 2.4L 4-cyl. engine.

Nitz does not expand on the application, but Ward’s reported last year it would appear in the new 2.4L direct-injection gasoline Buick Regal when production of the sedan shifts in first-quarter 2011 to Oshawa, ON, Canada, from Russelsheim, Germany.

Nitz says the new BAS system provides a 20% boost in fuel economy and suggests it could serve as the basis for future GM powertrains.