ALTON, VA – General Motors and Ford may prefer to tout fuel-economy numbers of their products in this new age of environmental friendliness, but there’s no doubt that a horsepower war continues to rage on the front lines of the pony-car segment.

“They are the ones playing catch-up,” says Al Oppenheiser, chief engineer of the Chevrolet Camaro and its newest variant, the 580-hp ZL-1 model. “We’re outselling (Ford).”

The Camaro accounted for 88,249 deliveries in 2011 and a leading 39.6% market share of the Middle Specialty segment, according to WardsAuto data. Sales ended the year up 1.4% compared with 2010, the car’s first full sales year after a 7-year production hiatus between 2003 and 2009.

Mustang deliveries totaled 70,438 units in 2011, down 4.4%, to finish No.2 in the segment with a 31.6% share.

The Camaro arguably continues to benefit from its fifth-generation redesign and the relatively recent arrival of a convertible model. The range-topping ZL-1, a fourth variant for the nameplate, goes on sale this month.

The current Mustang, also in its fifth generation but on sale in the U.S. uninterrupted since it spawned the pony-car segment in 1964, was last redesigned for ’05. New styling is expected in 2014, WardsAuto product cycle show.

Meanwhile, Ford continues to crank out specialty versions of the Mustang, such as a ’13 Shelby GT500 with 650 hp and a top speed of 200 mph (322 km/h).

The GT500’s performance numbers, which Ford revealed at the Los Angeles auto show in November, surpass the ZL-1’s 580 hp and top speed of 184 mph (296 km/h), which GM revealed ahead of the LA auto show.

GM first tipped its hand about output of the ZL-1 supercharged 6.2L V-8 at the Chicago auto show one year ago, promising “a minimum” of 550 hp. At the time, it would have at least duplicated the 550 hp coming from the ’12 GT500’s supercharged 5.4L V-8.

“When the final numbers came in at 580 hp, we were cheering,” Oppenheiser tells WardsAuto at media preview of the ZL-1 here.

It’s not the first time Ford has flanked GM on horsepower. In the ’10 model year, Ford increased output of the Mustang’s base 4.0L V-6 to 315 hp from 300 hp to trump the 305 hp from the Camaro’s standard 3.6L V-6 engine.

GM answered that in ’11 by nudging the V-6 engine’s output to 312 hp. It makes 323 hp for ’12. By dropping production of the 4.0L V-6, the ’12 Mustang’s entry-level output from its 3.7L V-6 sits at 305 hp.

The one-upmanship has carried over to the truck segment, where the ’11 Chevy Silverado and GMC Sierra Heavy Duty pickups equipped with a turbocharged 6.6L V-8 diesel engine makes 765 lb.-ft. (1,037 Nm) of torque. They initially overtook the 735 lb.-ft. (997 Nm) from the Ford F-Series Super Duty’s 6.7L turbo diesel V-8.

Ford came back just weeks after GM’s torque announcement with a revised torque rating  of  800 lb.-ft. (1,085 Nm) of torque for the Super Duty.

“I think we’re both playing our cards pretty well,” Oppenheiser says of the gamesmanship between the auto makers. “And we both benefit, because it brings more attention to the pony-car segment.”

However, he credits the horsepower competition more to undecided voters than blue-blooded Ford and Chevrolet buyers.

“Ford people are going to buy a Mustang; Chevy people are going to buy a Camaro,” Oppenheiser says. “It’s the people in between you need to get.”