DETROIT – Looming global regulations calling for increased fuel economy and reduced emissions have auto makers thinking outside the box in developing high-tech powertrain solutions.

Long-term strategies differ to some degree, but auto makers and suppliers on hand for a panel discussion here all say they are approaching the challenge from a total-systems perspective.

“A (total) powertrain approach is required, (including) both engine and transmission efficiency,” Makoto Yasuda, Nissan vice president-powertrain, says at the 2013 SAE World Congress. “An evolution of the power source will be essential.”

The trick, engineers say, is to limit losses that occur with today’s powertrains in order to squeeze out every bit of energy from a gallon of gasoline or other fuel.

Bob Lee, Chrysler vice president-engine and electrified propulsion, says to achieve upcoming U.S. fuel economy and emission targets the auto maker is focusing on several core technologies that could be used on vehicles worldwide, including 8- and 9-speed automatic transmissions and the Fiat-engineered Multiair valve-control system.

“We’ve gone through the technologies and made huge investments,” he says.

The next challenge is to make these components and systems even more efficient while at the same time engineering more advanced technologies, he says.

While improving efficiency is critical, Lee says Chrysler is striving to develop technologies customers will embrace.

Some auto makers are looking to electrified powertrains to achieve upcoming fuel-efficiency standards, but Lee says Chrysler views that as a long-term solution because today’s buyers are unwilling to pay for the technology.

“The engineering challenge is to drive (down) vehicle energy demand as low as we can,” he says. “We want the highest efficiency possible.”

Nissan’s Yasuda agrees with the total-systems approach, but adds a few twists. He says to reduce carbon-dioxide emissions, traffic congestion must be alleviated and consumers should be taught eco-friendly driving tips.

The Japanese auto maker’s powertrain strategy revolves around energy-loss mitigation, regeneration of lost energy and utilization of additional power sources such as lithium-ion batteries.

The first step, he says, is to eliminate common causes of energy losses, including high temperatures and friction.

And without systems that recapture energy, such as regenerative braking systems, Yasuda says “conventional powertrains have a theoretical limit” to CO2 reduction. “We have to think beyond conventional technologies.”

Yasuda says Nissan will concentrate on optimizing conventional powertrains while developing advanced hybrid, plug-in hybrid and pure-electric vehicles.

Joe Bakaj, Ford vice president-powertrain engineering, says a total vehicle-energy analysis by the auto maker shows the vast majority of energy from a fuel source is wasted as a result of heat, friction and pumping and mechanical losses.

Only 27% of the total energy is used to propel a vehicle, and even that is depleted by aerodynamic inefficiencies and rolling resistance of its tires.

Like Chrysler, Ford has identified systems that deliver the best bang for the buck, Bakaj says, citing electronic power steering, active grille shutters, hybrids and battery-electric powertrains as fundamental technologies.

“We’re now rolling (the technologies) out on high-volume platforms and working on the next-generation building blocks,” he says.

Ford’s line of low-displacement turbocharged EcoBoost engines also is critical to its long-term fuel economy and emissions-reduction strategy, he says, noting the auto maker offered seven vehicles with an EcoBoost engine in 2011 and now markets 15.

“The key challenge is now handling the wide variety of powertrain choices and making them affordable,” Bakaj says, noting Ford’s “power of choice” strategy involves offering a number of solutions to consumers.

“The power of choice hinges on high-volume platforms to be compatible with a lot of technologies,” he says. “That gives us economies of scale and the flexibility to change the mix depending on consumer demand.”