The numbers are in, and they've been certified by the feds, so it's official: The 2011 Mustang V-6 puts down 305 horsepower and gets 31 mpg on the highway.

The Environmental Protection Agency completed testing the V-6 Mustang this week, and Ford said Thursday it's the first time a production car has made more than 300 horsepower while returning more than 30 mpg.

We couldn't come up with a car to refute that claim – if you can, let us know – but even if Ford's blowing smoke, it's still an impressive accomplishment. It one-ups the Chevrolet Camaro, suggesting we're on the cusp of a new kind of muscle-car war, and it highlights the gains yet to be made in internal combustion engines even as the industry flirts with hybrids and EVs.

"This is a milestone for Ford and for the auto industry," said Ron Cogan, editor of Green Car Journal. "This is a big statement."

It's nothing for a hybrid like the 2010 Toyota Prius to hit 50 mpg or more, and even a rolling bank vault like the Cadillac Escalade Hybrid can get 22 combined. But we're talking about a muscle car that can smoke the tires and get Honda Civic–like fuel economy on the highway.

"When you've got a mainstream car like the Mustang that can give you 31 mpg and the performance car enthusiasts expect, it's just short of amazing," Cogan said.

The figures apply to the V-6 with a six-speed automatic gearbox. It's good for 19 city/31 highway. Choose the standard six-speed manual and you'll get 19/29. Obviously these figures depend upon the force with which you're depressing the gas pedal, but they're the official EPA figures you'll see on the window sticker.

To put those figures in perspective, the new V-6 Mustang has 95 more ponies than the dog car it replaces and improves the outgoing model's fuel economy by 4 mpg. The highway fuel economy is 1 mpg more than Ford expected.

"The Mustang engineering team aimed high and, through hard work, achieved fuel-economy numbers that elevate Mustang into a class by itself," Derrick Kuzak, Ford group VP, said in a statement.

So how'd they do it?

The 3.7-liter engine is made of aluminum to reduce weight. It's got cold-air induction and variable cam timing to optimize efficiency. Ford tweaked the gear ratios and shift program in the transmission to maximize fuel economy. The hydraulic power-steering pump was ditched in favor of an electric unit to cut parasitic drag on the engine. And the aerodynamics were improved with a new front fascia, a taller air dam and tighter seals on the trunk, among other things.

Together the modifications "speak to the future of Mustang," said Barb Samardzich, Ford's VP of global powertrain engineering. "We've proven that, using technology, Ford can deliver both power and fuel economy."

Ford is hardly alone in doing this. Everyone is using direct injection, turbocharging and other tricks to maximize performance and efficiency, and we're seeing these mods in muscle cars as well as compacts. Order a 2010 Camaro with a V-6 and an automatic, and you'll get 22 city/29 highway in a car putting down 304 horsepower.

"GM surprised people, and I’m sure Ford used that as a target to beat," said Mike Omotoso, an industry analyst with J.D. Power & Associates. "I suspect that Chrysler will try to get 30 mpg highway with the V-6 Challenger if or when they put the Pentastar V-6 engine in it."

Ford didn't use direct injection in the V-6, and Omotoso says adding that would probably boost fuel economy another 10 percent. Give it a smaller engine with a turbocharger – in other words, one of the Ecoboost engines – and it will will climb higher, still without sacrificing performance.

Hybrids and EVs might be the hot trend in the auto biz, but no one expects internal combustion to go away anytime soon. Automakers are doing everything they can to squeeze more efficiency and performance from their engines, and Cogan says there's still a lot of improvements to be made. Diesels can routinely break into the 40s, and Cogan's confident gasoline engines will join them before long.

"I don't see any reason why an internal combustion engine couldn't get 50 mpg," he said. "But it takes new thought and a new approach that maximizes efficiency while balancing the need for performance."

Omotoso, who follows powertrain development specifically, is even more optimistic. Automakers will continue squeezing more efficiency from their engines for a long time to come, as government regulations and consumer demands force them to.

"I’m not sure if there is an upper limit in terms of efficiency, but if there is, we are not close to it yet," he said. "Less than 30 percent of the energy in gasoline is converted to power in the vehicle, so we have a long way to go."

Photos: Ford