ROUEN, France – Fiat Automobiles SpA’s strategy for meeting Europe’s 2014 Euro 6 rules for a 56% reduction in oxides-of-nitrogen emissions is the opposite of PSA Peugeot Citroen’s approach.

The French auto maker plans to tune its engines for fuel efficiency and use aftertreatment technology to treat the extra NOx, while Fiat intends to reduce NOx at the engine-out phase to a level that doesn’t require aftertreatment.

Fiat further is developing its MultiAir valve control already in production on gasoline engines to maintain better control over combustion, says Marco Tonetti of Fiat Powertrain Technologies.

He makes his remarks at a conference here on the future of the diesel engine, sponsored by SIA, the French automotive engineering society.

“Cost is a key point for the survival of diesel engines,” Tonetti says, and by adapting the existing MultiAir technology to diesels, Fiat can reduce costs by achieving higher volumes on components and avoiding aftertreatment systems.

MultiAir was introduced last year on a 1.4L engine in the Alfa Romeo Mito and now is being expanded to all Fiat’s gasoline engines, including the 2-cyl. gasoline and compressed-natural gas engine being designed for the Fiat 500.

The technology will be used on the Family B 1.6L and 2.0L diesels by 2014.

“It is the best solution in terms of cost benefit,” says Tonetti, noting carryover parts from the gasoline MultiAir include the solenoid, valve, brake, accumulator and pump piston.

The system uses two hydraulically activated cams for the intake valves. They can be controlled for different engine conditions, from cold start to high power.

The basic engine strategy will re-circulate low-pressure cool exhaust gases into the combustion chamber to reduce NOx production, but the valve control also can open an intake valve during the exhaust cycle to capture exhaust gases directly.

“NOx peaks in transients are reduced because the internal exhaust-gas recirculation can guarantee a constant level at the cylinder while the intake system is being refilled by low pressure EGR,” Tonetti says. The system will meet Euro 6 without aftertreatment while still improving fuel economy 2%.

“For 2015, OEs can choose between different approaches,” says Juergen Gerhardt, senior vice president-diesel system engineering at Robert Bosch GmbH. “But for 2020, they can combine all of them.”

In 2020, auto makers in Europe are expected to meet a fleet average of 95 g/km of carbon-dioxide exhaust, and there may be new anti-pollution rules as well.

Gerhardt says 95 g/km over the fleet is doable because “now the end customer is willing to purchase these cars. There were fuel-efficient cars in 2000, but nobody bought them.”

Engineers from Bosch, Continental AG and Delphi Corp., the three main suppliers in Europe of high-pressure common-rail direct-injection systems for diesels, all are working on ways to improve fuel consumption.

They are redesigning injector nozzles, raising common-rail pressures beyond 29,000 psi (2,000 bar) and developing electronic-control strategies to get more mechanical energy out of combustion.

The industry believes the diesel engine will survive as long as it more fuel efficient, even though it’s more expensive.

Helmut List, CEO and founder of Austrian engine-specialist AVL List GmbH, says hybridization will guarantee a long life for diesel engines, because the addition of a 15 kW (20-hp) electric motor in a powertrain will give engineers a lot of flexibility in designing how an engine should work.

“There are so many solutions, you can hardly find the best one,” says List. “There is a good future for diesel, but a challenging one for costs. We can improve efficiency 10%-20% in the coming 10-15 years, maybe even more.”

Most auto makers, such as PSA, are adding aftertreatment systems for NOx, using either selective catalytic reduction systems or NOx traps, but List says there is no clear movement toward one over the other.

One trend that is clear for fuel efficiency is engine downsizing.

Renault SA and AVL present a paper here for an “aggressively downsized diesel” engine that is a 3-cyl. with the same bore and stroke as Renault’s 4-cyl. K9K diesel and would match the K9K’s 107 hp.

While the prototype is not intended for production, the exercise suggests several paths to follow, the two companies say, including a new way to mount a 3-cyl. engine to reduce vibration and the benefits of a 2-valve approach over four valves per cylinder.

PSA already is working on a family of 3-cyl. diesels, but Fiat Powertrain takes it to another level. “If we need to downsize diesel, we would go to two cylinders, not three,” Tonetti says.

As another approach to reducing costs, he says Fiat is investigating the idea of using the same engine block for diesel and gasoline engines with the same MultiAir cylinder head, so a single line could produce both engine types with only minor differences in machining.