By G.R. Whale
Lighter vehicles mean better fuel economy, so since the 1975 enactment of federally mandated corporate average fuel economy standards, all vehicles — pickup trucks included — have gone on a long-term diet, shedding weight with each redesign. Besides helping the environment by reducing oil consumption, lighter vehicles also are easier to stop, accelerate and turn. Pickup trucks included.
So how have truckmakers helped pickups lose weight over the years?
All pickup manufacturers are learning to save weight, as we've seen with Ford's extensive use of aluminum on both their light- and heavy-duty models, as well as General Motor's "mixed-materials" strategy. The forced diet started with finding lighter-weight materials from which to manufacture components. Take engines, transmissions and transfer cases; 20 years ago they were made of iron. Now nearly all of them are made from aluminum, the exceptions being the engines found in some heavy-duty pickups. That means about 80 percent of pickups are equipped with aluminum engines, transmissions and transfer cases. Aluminum now can be found in suspension systems and front differentials as well.
Many drive shafts also are made from aluminum nowadays, but the additional costs and exposure to harsh environments will likely prevent pickup drive shafts from ever being made from the lightweight carbon fiber found on some performance cars.
Impact of Weight
It's commonly claimed that a 10 percent weight reduction nets a 5 to 7 percent decrease in fuel consumption. But it's difficult to check that claim. The only test we could come up with is comparing an empty truck with an identical truck loaded with 10 percent more weight. When we've done that, fuel economy improves for city driving but not for steady, long-haul highway cruising.
When Ford introduced the all-new aluminum 2015 Ford F-150, its EPA ratings beat the CAFE guidelines for its segment. That's not surprising given the pickup's more aerodynamic exterior and light-weighting changes. However, in PickupTrucks.com's Texas Truck Showdown 2016: Max Towing, the steel V-8 2016 Chevrolet Silverado 1500 outweighed the aluminum V-6 2016 Ford F-150 by 500 pounds and posted slightly better mpgs in a real-world fuel economy test. The Chevy got 23.9 mpg combined when driven empty while the Ford came in at 22.8 combined.
Class 8 trucks — big rigs and tractor trailers — have used aluminum frames for decades. Last year Class 8 manufacturers Alcoa and Metalsa showed an all-aluminum commercial truck frame that reduced vehicle weight by 900 pounds compared to previous versions. However, our sources at Alcoa were unaware of any pickup manufacturer using, or even contemplating, an aluminum frame, although some work has been done with aluminum cross-members.
Right now all pickups use some aluminum in the drivetrain and most wheels; Ford builds most of a pickup's body from it, and GM and Ram use it in hoods. That helps lighten the load. However, all full-size pickups have a steel frame, and steel can still be found in some of the bodywork (Ford's F-Series included).
The Honda Ridgeline and Toyota Tacoma employ sheet-molded composite for their inner cargo beds. We were told Toyota considered changing the Tacoma bed to high-strength steel for 2016, but found that midsize owners appreciate composite for its utility, durability and value relative to a steel bed that requires a drop-in or spray-in bedliner for dent and anti-corrosion protection.
Carbon fiber is light and strong, but not cheap. While carbon-fiber-reinforced polymers have been investigated for B-pillar support in pickups, there are concerns about attachment points. We don't see carbon fiber making big inroads in pickup trucks in the near future. Magnesium applications likely will be limited to instrument panel beams, inner door panels and locations not susceptible to corrosion.
Aluminum use will continue to grow: A 2014 Ducker Worldwide study suggests that completely aluminum-bodied vehicles will double by 2020, and by 2025, seven of 10 pickups will be aluminum bodied. We're guessing the higher profit margins on half-ton pickups will justify restricting use of aluminum to that segment, although Ford is basing the body strategy of the 2017 Super Duty on the F-150. Wall Street Journal report suggested that the next Chevrolet Silverado/GMC Sierra will have aluminum bodies. Use of high-strength steel will keep growing in pickup frames and certain crash structures such as the F-150's side door beams and wheel well tubes. It also will be found in lower-volume vehicles that don't justify the expense of plant switchovers to aluminum.
Both the aluminum and steel industries tout their materials' environmental benefits, which include recycling. Recycling materials can help keep production costs in check. Ford recycles 20 million pounds of aluminum stamping scrap every month, equivalent to 30,000 SuperCrew standard-bed F-150s. Rather than trashing the scrap aluminum, Ford cycles it back into its production process to make brand new F-150s.
On the topic of recycling, the biggest advantage of aluminum is that it can be melted down with little structural change, so it won't degrade much from one life cycle to the next. That's not true with steel; each time it is melted down and reshaped, new uses must be found. The commonality here is that these materials allow truckmakers to save money through recycling; those savings can be passed along to consumers.
Our advice to truck buyers and truckmakers is the same: Keep recycling everything you can. It might make our new trucks cheaper.