The free ride for Detroit's big pickups likely will come to an end in 2014, when U.S. corporate average fuel economy rules are expected to snap up the long-exempt heavy haulers for regulation.

Later this month, the National Highway Traffic Safety Admin. and Environmental Protection Agency will release a Notice of Intent to Issue a Proposed Rule for 2017-2025 light-vehicle fuel-economy and emissions standards, as mandated in May by President Obama.

For the first time, the agencies are expected to suggest a rulemaking approach for vehicles between 8,500 lbs. (3,856 kg) and 10,000 lbs. (4,536 kg) gross vehicle weight. The pickups have been exempt from CAFE since the program started in 1975.

But unlike light-duty vehicles within the "2017 and beyond" CAFE rules, regulation of the big pickups would begin in 2014, and Obama wants a final rule for them by July 30, 2011.

While not unexpected, the rules would rein in the regulatory freedom General Motors Co., Ford Motor Co. and Chrysler Group LLC have enjoyed with their Chevrolet Silverado HD, GMC Sierra HD, Ram HD and Ford Super Duty pickups.

Asian and European OEMs do not sell pickups in that weight class in the U.S., leaving hefty profits from the segment to Detroit. According to Ward's data, heavy-duties historically account for about 30% of Detroit's annual pickup sales.

Fuel-economy experts do not anticipate the pending rules would cut too deeply into Detroit's research budgets.

"Look for technology from light-duty (trucks) to help them; there should be some cost savings there," says Don Anair, senior analyst-vehicle program at the Union of Concerned Scientists. UCS research influences CAFE rulemaking.

"I don't expect them to have to come up with brand-new technology" to meet the new standards, he tells Ward's, citing technologies such as mileage-boosting direct injection for gasoline engines and higher turbocharging capacities and selective catalytic reduction for diesels.

Although the Bush Admin. CAFE reform rules creating the new footprint system taking effect with the '12 model year captured some big SUVs, such as the Ford Excursion and Hummer H2, Detroit's HD pickups remained excluded.

Exclusion of the pickups dates back to the beginning of CAFE, when GVWs mostly were under 6,000 lbs. (2,722 kg) and the trucks were used almost entirely for work purposes. As such, NHTSA used its discretion to exempt them.

Seeing a trend in the 1980s to bigger vehicles, the agency ratcheted up CAFE to 8,500 lbs. GVW. In response, Detroit auto makers migrated the trucks over the regulation cap, and low fuel prices meant consumers easily could upsize. Detroit since has fought to keep CAFE out of the segment.

Detroit's motivation was obvious: Single-digit fuel economy from earlier HD pickups would hinder an OEM fleet's ability to meet CAFE. Even the modern powerplants evaluated in the Best Engines Diesel Shootout could not reach 12 mpg (19.6 L/100 km) with trailers attached.

"We're hoping they will be more proactive going forward," Anair says of Detroit auto makers.

It is widely expected any coming regulation would be separate from an auto maker's light-vehicle CAFE average.

The historic new light-vehicle CAFE standards were adopted last year.

Average MPG during Diesel Shootout

Ford: 11.5 (20.43 L/100 km)

GM: 11.7 (20.0 L/100 km)

Dodge: 11.6 (20.25 L/100 km)