By Bruce Geiselman
Automakers are embracing electric vehicles (EVs) at a rate that signals the biggest change in the history of automobiles and light trucks.
The plastics industry will benefit because vehicle lightweighting — a mantra for the past decade — will become even more important to offset heavy batteries.
“The batteries in electric vehicles are very, very heavy,” said Shashank Modi, a research engineer with the Center for Automotive Research (CAR), a nonprofit think tank in Ann Arbor, Mich.
“To offset that weight, you have to take that weight out somewhere else,” Modi said. “You have to use lightweight material in the body structure of the vehicle. You have to not only offset the weight, but you have to actually make the vehicles lighter because there are range-anxiety issues with the electric vehicles. The lighter the vehicle is, the more range you can get with the same battery power.”
General Motors recently announced it will make its global products and operations carbon neutral by 2040. As part of its plan, GM will offer 30 all-electric models globally by the middle of this decade, and 40 percent of the company’s U.S. models will be battery EVs by the end of 2025.
In February, Chevrolet expanded its EV portfolio with the all-electric 2022 Bolt EUV (Electric Utility Vehicle) alongside its redesigned 2022 Bolt EV.
GM’s carbon-neutrality pledge followed a similar announcement by Ford in 2020 that it intends to achieve carbon neutrality globally by 2050. Its strategy includes new all-electric vehicles, such as the zero-emission Mustang Mach-E, a Transit Commercial EV and a fully electric F-150 pickup truck, which are in the pipeline.
Their plans follow in the footsteps of Europe’s largest automakers.
“That is definitely a trend that we are seeing,” said Modi. “European automakers made those promises ahead of the North American automakers. American automakers will catch up. Climate change and sustainability is becoming very important, and all these automakers support the UN sustainability goals. Moving to electric vehicles is one way to be sustainable.”
In addition, automakers are reducing factory emissions and improving the fuel efficiency of gasoline engine vehicles — but increasing the production of EVs plays a major role in helping automakers meet their sustainability goals, Modi said.
EVs tend to weigh more than vehicles with traditional engines, Modi said. While lightweighting auto parts is nothing new, the shift toward EVs is increasing the pressure on automakers to reduce vehicle weight wherever possible.
Substituting plastic for metal is one option, but plastic is facing competition from new, stronger metal grades.
“Lightweighting will benefit plastics, but it will also benefit other metals like aluminum and steel,” Modi said. “They have been dominant in the automobile industry, and they are working on various technologies to produce high-strength steel and new aluminum grades. When you increase the strength of the material, you can reduce the gauge and therefore lightweight [it]. Plastics have an increasing opportunity, but so do other materials as well.”
One way that OEMs are reducing body weight — in both EVs and traditional vehicles — is using polymer composites for structural components. For example, the insides of doors, fenders and liftgates increasingly are being reinforced with glass-fiber and/or carbon-fiber composites, which reduce the need for metal reinforcement. Such reinforcement also is being added to floors, pillars and roof rails.
Automakers can choose between continuous or chopped glass or carbon fibers depending on the application, Modi said. They also are looking at adopting greener materials, such as natural/biofiber composites incorporating hemp, flax, sisal or jute.
“Some research is going on toward using biomaterials for the fiber,” Modi said. “Instead of using carbon fiber, which is a petroleum product, in the future, we could see more biomaterial applications in that area.”
PC is increasingly common in car roofs. “There has been a trend to move to polycarbonate for sunroofs because it’s lightweight, and with those panoramic sunroofs that we see, it’s a significant weight savings,” Modi said.
Pickup truck beds are another area where composites are making inroads. For example, GMC’s Sierra Denali truck bed is made with a carbon-fiber reinforced polymer, while beds from other manufacturers typically are constructed of steel or aluminum, Modi said.
Lightweighting is taking place in traditional internal combustion engine vehicles as automakers try to boost mileage to meet government standards.
In the U.S., the National Highway Traffic Safety Administration’s Corporate Average Fuel Economy (CAFE) standards regulate how far passenger cars and light trucks must travel on a gallon of fuel. Improving mileage also helps reduce carbon emissions.
In Europe, automakers are trying to meet legislated emissions standards.
In September, California Gov. Gavin Newsom issued an executive order requiring all new passenger vehicles sold in the state to be zero-emission by 2035.
Low-strength steel is being replaced by high-strength steel, aluminum, and polymer composites, according to a CAR white paper.
Automakers are using engineered thermoplastics in battery enclosures for EVs, which keeps the weight down while protecting vehicle occupants.
“For EVs, you need a battery box, basically a battery enclosure, that can hold the batteries that the system needs and is flame retardant,” Modi said. “It needs to protect the occupants from fire hazards. Therefore, it should withstand high temperatures. Engineered thermoplastics are being developed that can be used for these high-temperature applications.”
Looking under the hood
Dan Hearsch, a managing director of management consulting firm AlixPartners and a leader in its automotive industrials practice, said automakers are reducing weight by shifting from metal to plastic parts under the hood.
“There are some grades of plastic that have been developed that are highly heat resistant and structurally stronger,” Hearsch said. “There are construction methods that allow for different types of plastics to be used for structural members. Things like thermostats and pump housings that maybe traditionally have been metal for heat-resistant purposes in under-hood applications are now types of nylon — nylon 6 and nylon 6/6. They’re both strong, but the most important piece is that they are able to resist high temperatures in those applications.”
“The trend right now is lightweighting,” Hearsch said. “It’s finding ways to take mass out of the car to improve efficiency, fuel efficiency or emissions efficiency, which is the key driver. It’s not really a cost play. It doesn’t take cost out necessarily. Sometimes it adds costs, but the whole point and the primary shift has been for taking weight out of the car.”
Nylon parts going under the hood often are talc- or glass-filled.
“It will have some type of material to add structural integrity but also to take cost down,” Hearsch said.
Talc is less expensive than resin.
Down the road
Hearsch described lightweighting as a mature movement.
“We’re not in the first inning,” Hearsch said. “We’re in the sixth or the seventh. There is certainly room to go, and the move to EVs changes the game a little bit.”
For the most part, heavy-duty structural chassis members and body panels still aren’t plastic, he said. That could change as new materials and technologies are developed that allow plastics to offer better structural integrity.
“Potentially, you could have plastic car panels that are more crashworthy than they are now, but for the most part, you will continue to see metal and metal cross members holding the vehicle together,” he said.
However, if all-electric, fully autonomous cars become a reality, that could spur a major revolution in car ownership and manufacturing.
“When you’re talking futurist-type things, by 2040, there’s a reasonable expectation that autonomy is much more prevalent,” Hearsch said.
If technology advances to the point where cars drive themselves without any human intervention other than instructing a car where to go, then the need for structural protections could change, Hearsch said.
“Vehicles that can communicate with each other faster in an undistracted environment that always know where other vehicles are really don’t run into each other anymore,” Hearsch said. “So, you can start to take out some of these protective structures like crumple zones that are protecting the occupant [and] creating an occupant cockpit that can’t collapse. If you get rid of all that, now it’s much safer for cars to be primarily plastic.”
Metals might still be necessary to support the batteries, occupant and motor, but a large portion of the rest of the vehicle could easily be transitioned to high-tech plastics, Hearsch said.
Hearsch is not alone in foreseeing the possibility of cars one day driving themselves.
“Future cities will likely be dominated by automated, connected, electrified, and shared (ACES) vehicles,” Modi and Abhay Vadhavkar, a CAR colleague, wrote in a white paper for CAR titled “Advancing Additive Manufacturing into the Mobility Industry.”
GM alone is investing $27 billion in electric and autonomous vehicles in the next five years, up from the $20 billion planned before the onset of the COVID-19 pandemic.
If fully autonomous electric cars become a reality, Hearsch also foresees a possible change in vehicle ownership. Instead of individuals owning their own cars, they could use them on a subscription basis. Riders could summon a vehicle when needed, tell it where they want to go, and avoid the hassles of owning, maintaining and parking their own cars.
“The potential is there within 20 or 25 years for that to exist,” Hearsch said.
Bruce Geiselman, senior staff reporter
AlixPartners, New York, 212-490-2500, www.alixpartners.com
Center for Automotive Research, Ann Arbor, Mich., 734-662-1287, www.cargroup.org