Lightweighting: Putting EVs on a Diet


larry fisher, a former New York Times reporter, writes about business, technology and design.

Published February 6, 2023


Cars are too heavy; electric cars are heavier still. And that’s really not a good thing.

Moving more mass requires more energy, so heavier cars are a retrograde step on the road to a net-zero carbon world. Heavier cars do more damage when they hit something or someone. In the United States, where big pickups and SUVs reign supreme, pedestrian fatalities increased by 46 percent from 2010 to 2019. The electric versions may reduce carbon emissions, but they weigh even more: Ford’s electric F-150 Lightning weighs 6,500 pounds, at least one-third more than the gasoline version.

“I’m concerned about the increased risk of severe injury and death for all road users from heavier curb weights and increasing size, power and performance of vehicles on our roads, including electric vehicles,” Jennifer Homendy, chair of the National Transportation Safety Board, said in a speech in January. She singled out General Motors’ EV Hummer, which weighs over 9,000 pounds. “The battery pack alone weighs over 2,900 pounds — about the weight of a Honda Civic,” she noted. “That has a significant impact on safety for all road users.”

Ever-heavier vehicles form a self-perpetuating loop of doom. People in small, light cars feel vulnerable amid the behemoths, so they buy bigger, heavier ones. Powering bigger cars requires bigger engines or bigger batteries, supporting them requires heavier suspension components, stopping them bigger brakes. So vehicles get heavier still. The energy density of lithium-ion storage is much lower than gasoline, so battery storage is bound to be a net loser on poundage. And on and on.

There is a solution: lightweighting. One of those rare technologies that means just what it says, lightweighting is the removal of excess avoirdupois through the use of lighter materials and more mindful design and manufacturing. It had a moment in the sun when the federal government’s corporate average fuel economy (CAFE) standards took effect, and auto manufacturers scrambled to shed pounds. Ironically, the shift to electric vehicles means car makers no longer need to worry about fuel economy and are not incentivized to spend money reducing weight. 

“Once you go green with electric, there is no CAFE,” lamented Andrew Halonen, a lightweighting specialist with Mayflower Consulting. “With the Ford I own, the government helped push the weight down. As soon as Ford goes electric, CAFE goes away, weight goes to the moon and nobody cares.”

Simplify and Then Add Lightness

Lightweighting is nothing new, though the portmanteau seems to have emerged only in the last decade. Colin Chapman spoke the above aphorism in the early 60s and applied the concept to take Lotus Cars to five Formula One World Championships. Chapman’s road-going Lotus Elan weighed a scant 1,250 pounds; by comparison, the 2023 Mazda MX5 Miata weighs 2,341 pounds, and still manages to be the lightest car currently sold in the U.S.

For most automakers, weight was a secondary consideration. But airframe manufacturers and bicycle builders have long embraced lightweighting, turning to increased use of aluminum, high-strength steels and carbon-fiber composites. A lighter aircraft can fly faster and farther on less fuel; a lighter bike makes the most of a rider’s single person-power.

But the Golden Age of lightweighting was the era of CAFE and the government incentives that came with them. The Energy Department calculated that reducing a car’s weight by only 10 percent could improve fuel economy by 6 to 8 percent, and it spread development awards among General Motors, Ford and Caterpillar, as well as to two federal laboratories.

Cost was always the elephant in the room. Alcoa acknowledged that it ran $600 to $800 more to use aluminum rather than steel to produce what automakers call a “body in white” — the car’s basic structure before moving parts like doors and engines are installed. But the weight savings were real: the 2013 Range Rover’s all-aluminum body made it 39 percent lighter than earlier models. Ford’s aluminum-bodied F-150 pickup, introduced in 2015, saved 700 pounds over its steel ancestors.

But, on average, cars kept getting heavier anyway, and with the coming of EV incentives the industry lost interest in reducing weight. The BMW i3, the company’s first production electric car in 2013, had an upper-body structure of carbon-fiber-reinforced plastic sitting on an aluminum chassis. So did the original Tesla Roadster, which perhaps not coincidentally was made for the California company by Lotus in the UK. But the BMW i4, just reaching the U.S. now, and all subsequent Tesla models are made of steel — and there are no lightweights among them.

“In the OEMs’ defense, how many customers have any clue what their vehicle’s weight is?” asked Halonen, using an industry acronym for original equipment manufacturers. If auto companies are “trying to bring value to their customers, is it about weight, or is it about sexy commercials on the Super Bowl? Where is weight in that picture? It’s probably lost in the noise.”

In the long run, using less fuel or fewer electrons is not only green, it’s an economic win. GE Aviation notes that every pound eliminated on a Boeing 737 reduces annual operation costs by hundreds of thousands of dollars — over the life of the aircraft, by many millions.
From Deception to Disruption 

Now for the hopeful part. Disruptive technologies, as per business-guru Clayton Christensen’s The Innovator’s Dilemma, tend to fly below the radar before their potential is visible. When Wozniak and Jobs demonstrated the Apple 1 prototype at the Homebrew Computer Club, few imagined that huge mainframe computers were an endangered species. Some experts say lightweighting’s transformation of transportation is advancing apace, just quietly.

Since the early days of flight, lightweighting has mostly been about hardware, swapping aluminum for steel, or eliminating excess weight. Or by simply removing it: bicycle racers used to drill holes in non-structural parts to shave a few grams. Some still do. But much of the progress in lightweighting today is driven by software innovation — topology optimization, AI-driven generative design tools and additive manufacturing, also known as 3D printing.

“All of this starts with new design thinking, by which I mean educating and inspiring a few generations of designers and engineers,” said Avi Reichental, founder and CEO of Nexa3D. “It starts and ends with design thinking that is grounded in lightweighting as an enabler. It must take advantage of the exponential progress of technologies that we are enjoying today.”

Let’s unpack a few engineering buzzwords here. Topology optimization is a mathematical method that optimizes material layout within a given design space for a given set of loads, conditions and constraints. Generative design is an iterative process wherein a software program generates a specified number of outputs that meet specified constraints so that a designer can fine-tune the desired product step-by-step. (The designer needn’t be human.)

Additive manufacturing combines software with hardware, rather the way Canon’s laser printers enabled Apple and Adobe to introduce desktop publishing. 3D printing, direct digital manufacturing, and rapid prototyping create a product by adding to, rather than subtracting from (as in traditional lightweighting). Additive manufacturing builds up whatever engineers want to build, are trying to build or dreaming of building, layer by layer — and in advanced nano-level additive manufacturing, literally molecule by molecule.

Taken one by one, each of these technologies is an enabler. Taken together, they should make possible new transportation alternatives that are not only lighter, but stronger, safer and more sustainable.

In the long run, using less fuel or fewer electrons is not only green, it’s an economic win. GE Aviation notes that every pound eliminated on a Boeing 737 reduces annual operation costs by hundreds of thousands of dollars — over the life of the aircraft, by many millions.

Automakers already have their hands full managing the transition from internal combustion engine vehicles to EVs. So while they are investing in, and in some cases already deploying these tools, they are taking their time.

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The apparent inaction is deceptive, said Reichental. Divergent 3D, a company in Los Angeles, “already has a factory producing some lightweighted chassis components, and already has supply contracts to one or two of the Big Three. These kinds of technologies get disclosed, developed, publicized and then there’s a long period where it’s all available but nobody’s doing anything. Then the economic drivers come in. We are beginning to emerge out of that deceptive phase and into the disruptive phase.”

main topic: Transportation