TRAVERSE CITY, MI – Powertrain improvements have led the first push to meet new CAFE standards, but automakers will shift their focus to lightweighting as new products are designed to meet tougher rules phasing in from 2017 to 2025.

Up to now, automakers have had success improving fleet fuel economy through downsizing and turbocharging engines, hybridization and introducing more advanced transmissions.

However, according to a new WardsAuto survey of automotive engineers and designers sponsored by DuPont, powertrain moves largely are considered low-hanging fruit that soon will be unable to propel the industry’s progress in meeting tougher requirements beginning in 2017 and hitting 54.5 mpg (4.3 L/100 km) by 2025.

This strategy already is apparent with the introduction of the ’15 aluminum-intensive Ford F-150 fullsize pickup going on sale later this year, which is 700 lbs. (318 kg) lighter than its predecessor and is the first truly high-volume, mainstream vehicle to be made mostly of the light metal.

Almost 50% of the nearly 900 automotive engineers and designers responding to the survey say their companies are focused on lightweighting and use of lightweight structural materials to meet 2025 fuel-economy rules, although they emphasize continued powertrain advancements are crucial.

Engine efficiency programs and electrified powertrains were the next most popular choices on the survey, followed by adopting more diesel engines. (Multiple answers were permitted on some questions, resulting in percentages adding up to more than 100%).

However, when WardsAuto asked engineers the same question in 2011, engine efficiency and electrification topped the list. Lightweighting ranked third.

“There are probably a couple of reasons for the shift,” says Jeff Sternberg, director of DuPont Automotive Technology. “I suspect one of the reasons stems from several high-profile lightweighting examples, like the ’15 Ford F-150 and BMW i3 (electric vehicle). Another reason is the growing recognition that every pound reduced from a component can pay dividends in being able to downsize other parts of the vehicle. For example, if you take 10 lbs. (4.5 kg) out of an engine or exhaust component, you need much smaller and lighter fasteners.

“All these weight-savings contributions add up.”