– By AARON M. KESSLER

Detroit Free Press

WASHINGTON – If the Obama administration gets the 56 mpg new vehicle fuel-economy rule it wants for 2025, will you still be able to buy a nine-passenger Chevy Suburban to carry half the soccer team? Or a Ford F-150 to trailer a 20-foot bass boat to the lake?

Yes. But under the hood you may find a V6, a really hot V6, or a diesel, and maybe expensive hybrid technology.

It won’t get anything close to 56 mpg, and it won’t have to since its fuel economy will be judged only against similar vehicles.

“You’re still going to be able to tow that boat, you’ll still be able to get that sporty sedan, when 2025 rolls around,” said David Friedman of the Union of Concerned Scientists. “It’s just going to be a better vehicle that costs less to run.”

But automakers, who this week began airing radio ads attacking the higher standards, fear that tougher rules could cripple the industry by forcing production of vehicles consumers don’t want.

“Going to 56 mpg is essentially a 100 percent increase from where we are today,” said Gloria Bergquist, vice president of the Alliance of Automobile Manufacturers.

Government standards for fuel economy have barely changed in 30 years.

A LOT OF WORK TO DO

But from the models that hit showrooms in September — when the fleet target will be 29.7 mpg — to those that will be out in 2025, car companies will have a lot of work to do. Under a 56 mpg standard for 2025, marketers and consumers would be asked to build, sell and want cars and trucks that squeeze every drop of gas about twice as hard.

Proponents of a higher target say dealers’ lots won’t look much different in 2025 than they do now: from trailer-towing trucks to subcompacts, with only a small percentage of electrics. But innovations under the hood — from better gas engines to newer hybrid technology — could save consumers thousands of dollars on gas, offsetting anticipated higher sticker prices.

Opponents of the proposed rules see a future in which consumers could be forced into smaller vehicles they don’t want and where, regardless of fuel savings, expensive technologies could price some lower-end buyers out of the market.

“If auto companies could hit the standards and have the same price, nobody would care,” said Jeremy Anwyl, chief executive of Edmunds.com. “But when you raise the requirements, there’s a point at which things can fall out of alignment.”

The government’s Corporate Average Fuel Economy, or CAFE, standards remained essentially frozen for years, as political maneuvering by Congress blocked the National Highway Traffic Safety Administration from raising them.

In 2007, legislators overhauled the program, bringing the Environmental Protection Agency into the mix along with NHTSA itself, and made fundamental changes.

Most dramatic: Large and small vehicles are no longer in competition with each other.

Instead, each is judged based on its “footprint” — a formula based on the distance between the axles and a vehicle’s width. There is a curve, and each footprint has its own fuel economy requirement on that curve.

BALANCING ACT TO END

The result is that automakers don’t have to balance sales of SUVs with poor fuel efficiency and subcompacts that get better mileage to meet CAFE targets. If the SUV meets the fuel standard for its own footprint, the automaker can sell all it wants.

If a vehicle does better than its benchmark, an automaker gets credits it can apply to other vehicles in its lineup that might not hit their targets. It can bank them for the future, apply them to the three previous years, or even sell them to another manufacturer.

There are other aspects that might surprise consumers. The CAFE number a vehicle scores is not the same as the window sticker consumers see on the lot. So a 56 mpg target means window values in 2025 will be closer to 35 to 40 mpg. Quite a difference.

AIR-CONDITIONING INCENTIVES

Air-conditioning is also important, and another reason that getting to 56 mpg by 2025 isn’t as daunting as it first seems. Because air-conditioning fluids can be pollutants, the government gives generous credits for using cleaner systems. Just with those credits alone, a 56 mpg CAFE target becomes 50 mpg.

The CAFE program also uses what it calls a “harmonic average.” That means small improvements in the worst performers can make a bigger difference than large increases in already-efficient vehicles. The SUV going from 15 to 20 mpg could save more fuel – and count for more in the CAFE system – than a subcompact going from 50 to 65 mpg.

The Consumer Federation of America endorsed the 56 mpg target, after its extensive surveys found U.S. consumers wanted more fuel-efficient cars.

Because most buyers pay for a vehicle over time, CF’s analysis concluded, consumers save much more on gas costs each month than they would spend on higher car payments for more fuel-efficient vehicles.

Friedman of the Union of Concerned Scientists agreed.

“From the moment they walk off the lot in 2025, they’ll be ahead of the game from where they are now,” Friedman said. “Every month, they’ll see reduced expenses.”

An analysis last year by EPA and NHTSA calculated four cost scenarios for 56 mpg, and estimated that while the increase in the typical vehicle available in 2025 could be $2,100 to $2,600, a consumer would make all that money back from fuel savings in just two to three years (based on about 15,000 miles driven each year).

But automakers and dealers are not convinced and say vehicles could wind up being even more expensive.

Edmunds.com CEO Anwyl said some consumers may simply have trouble seeing past a higher sticker price. But there are some “easy wins,” Anwyl said, that wouldn’t raise costs much — like boosting efficiency of gasoline engines.

So far this year, Americans are buying more fuel-efficient models — including larger vehicles.

SOME HOT SUVS

Sales of the Chevrolet Equinox and GMC Terrain crossovers — rated at 32 mpg highway — are up more than 70 percent overall in 2011. “Those vehicles have basically been red hot for a year and a half,” said GM’s Tom Henderson. “They offer the utility people are looking for, along with the high mileage.”

And in the full-size truck market, buyers are embracing Ford’s new six-cylinder F-150s.

“There was this kind of myth, that truck buyers wouldn’t have any interest in a V6 engine,” said George Pipas, a Ford sales analyst. “They’ve been flying out of showrooms.”

The 3.5-liter V6 Ecoboost F-150 gets better mileage than its 5.0-liter V8 sibling, and yet actually delivers more horsepower and torque. The turbocharged truck is rated to tow more than 11,000 pounds. And it costs only $750 more than the V8.

Only a few months after the new V6s were introduced, nearly half of F-150 buyers were choosing them. By May, the majority were.

Ford has developed a four-cylinder version of the engine that’ll be in Explorers and Edges this year, and a three-cylinder is in development for smaller cars.

“I think we’ll see some things in a few years’ time that we never could have imagined was possible with a conventional engine,” Pipas said.

But conventional engines only get you so far.

Automakers have publicly suggested that a higher CAFE target would leave the public with no choice but to adopt electrics in large numbers.

“Fifty-six miles per gallon is really a mandate for electric vehicles,” said Bergquist of the Alliance of Automobile Manufacturers. “It’s a significant increase that no matter which yardstick you use, achieving those gains won’t be possible without electrification in a big way.”

Yet supporters of 56 mpg see pure electric vehicles and plug-ins as a much smaller percentage of the market by 2025.

“It’s not electrics that are going to get us there,” said the Union of Concerned Scientists’ Friedman, predicting electrics might reach 5 percent of the market.

Instead, he said, it would be improvements on conventional gas and diesel engines, as well as more and new hybrids.

The hybrid component — in a wide spectrum of forms — could ultimately bring the biggest change.

PLUG-INS A BLIP

Three of the four EPA and NHTSA scenarios calculated last year for what the 2025 fleet could look like at 56 mpg found plug-in or pure electrics as a blip — but the penetration of hybrid vehicles ranged from 25 percent to 65 percent.

That doesn’t mean a world of Toyota Priuses. Rather, a whole range of new options from stop-start to “mild” hybrids to more robust electric-gas combinations will enter the automotive bloodstream.

This year, General Motors is unveiling its new Buick LaCrosse and Regal with a feature called eAssist — a tiny electric motor that boosts the gas engine’s mileage. It’s a mild hybrid.

The driver might not even know it’s happening, at least until realizing the full-size LaCrosse is getting 36 mpg on the highway.