Nov. 13 (Bloomberg) -- General Motors Co. and Ford Motor Co., overhauling their lineups to focus on fuel economy, are in a muscle-car sales race that harks back to an era when speed trumped efficiency.

GM’s Chevrolet Camaro, which debuted in April, has outsold Ford’s Mustang in the U.S. for each month since June, according to industry researcher Autodata Corp. The Camaro boasts a bigger engine, with as much as 426 horsepower, over the former sports- car leader Mustang and its available 315 horsepower.

“We’re happy with Camaro’s performance,” Susan Docherty, GM vice president of U.S. sales, said on a Nov. 3 conference call. “It’s probably just bragging rights, but we haven’t led the sports segment since 1978.”

The matchup evokes Detroit’s 1960s embrace of V-8s at a time when the U.S. auto industry is spotlighting vehicles such as the Chevy Volt plug-in electric car. The difference now is that even the automakers see the Camaro-Mustang competition as a sideshow, not the future of their business.

“We’ve seen a few people go over to Camaro,” Steve Ling, Ford’s North American car marketing manager, said today in an interview. “We never stand still with Mustang. We have a track record of improving it every year. And that will continue to be the case.”

George Pipas, Ford’s sales analyst, estimated that sports cars account for about 2 percent of the domestic auto market.

Ford rose 21 cents, or 2.6 percent, to $8.41 at 4 p.m. in composite trading on the New York Stock Exchange. The shares are up 21 percent since Oct. 1 and have more than tripled this year.

Hybrids vs. Performance

U.S. sales of Toyota Motor Corp.’s Prius hybrid last month totaled 13,496, topping the combined tally of 8,082 Camaros and 4,789 Mustangs, according to Woodcliff Lake, New Jersey-based Autodata. Detroit-based GM plans a late-2010 debut for the Volt, and Ford will unveil its redesigned Fiesta subcompact at the Los Angeles Auto Show in December.

Camaro sales have been “weighted heavily” to the SS version with a V-8 engine, said Adam Denison, a Chevy spokesman. The 2010 SS averages 19 miles in combined city/highway driving and starts at $30,745, according to Edmunds.com, while the V-6 base model averages 21 mpg and begins at $22,680.

“We’re actually surprised to see” the SS outselling the base model, Denison said. “Even though the economy is shaky right now, this car does get good mileage. It’s a budget- friendly sports car.”

The 2010 Mustang GT Premium has a 315-horsepower engine and is rated at 19 mpg, according to Edmunds.com, the Santa Monica, California-based operator of auto-information Web sites. That version starts at $30,995.

‘Big Deal’

“The Camaro is eating the Mustang’s lunch because it beats the Mustang on key talking points,” John Wolkonowicz, an auto analyst at IHS Global Insight Inc. in Lexington, Massachusetts. “It has a larger V-8 engine, and in the muscle car arena that’s a big deal.”

Ford, based in Dearborn, Michigan, will remedy that deficit by introducing a more powerful V-8 next year, Wolkonowicz said.

Camaro models sold at an average of about $662 more than the sticker price in October, with the biggest premium on the SS models, according to Edmunds.com. Mustang rebates from May to October ranged from $1,784 to $3,280 compared with $434 to $1,139 for Camaro, Edmunds.com said.

Ford’s Pipas said the Camaro has pulled ahead because it is the newest sports car on the market and Chevy loyalists are snapping up the first version of the car produced since 2002.

“There’s a lot of pent-up demand for the Camaro,” Pipas said. “Over the last 10 years, we’ve sold 1 million Mustangs.”

Camaros account for as many as 17 of the 100 to 120 cars sold each month at Hare Chevrolet in Noblesville, Indiana, and all of them are sold before they get to the store, said Brad Smith, a sales manager at the dealership.

“I have never seen this much interest in a car,” said Ty Lowery, who handles Internet Camaro sales at Hare and previously sold Mustangs at a Ford dealership in Illinois. “The Mustang was really the only choice for an old-style American sports car for quite a while. It didn’t have any competition.”

To contact the reporters on this story: Keith Naughton in Southfield, Michigan at Knaughton3@bloomberg.net; Jeff Green in Southfield, Michigan, at jgreen16@bloomberg.net

Last Updated: November 13, 2009 16:19 EST