The Lightweight Advantage

How Lightweighting Reduces Energy Use

Vehicle design is a continuous balancing act between performance, efficiency, and cost – and material selection plays a key role. Among the various levers available to engineers, reducing a vehicle’s mass delivers significant energy savings across driving conditions.

In city driving, rolling resistance is one of the dominant sources of energy loss, responsible for roughly 30% of energy consumption in battery electric vehicles (BEVs). This resistance is directly proportional to vehicle mass, meaning that reducing weight results in lower energy use. But that’s just the beginning.

In internal combustion engine (ICE) vehicles, studies show that a 10% reduction in vehicle weight leads to a 3–4% drop in fuel consumption. Further, downsizing the engine in proportion to that level of weight savings can improve fuel economy by as much as 6%. This offers a dual benefit: lower fuel use and the potential for a smaller, more cost-effective engine.

In BEVs, where the battery is both the heaviest and most expensive component, lightweighting has even more value. Reducing mass by 10% typically results in a 4–5% reduction in energy consumption, enabling manufacturers to reduce battery size while maintaining the same driving range. This sets off a virtuous cycle: a smaller battery lowers overall vehicle weight further, opening the door to additional savings across components like the body, motor, brakes, and suspension.

Designing for Lightweight Efficiency

To understand the full lightweighting potential of aluminum, it’s important to consider the function and stress profile of the part being designed. Automotive components typically fall into two categories:

1. Stiffness-Dominated Parts
These are components that need to resist bending, like hoods, doors, roofs, and various inner stampings. Although aluminum has only one-third the stiffness of steel, thickness increases have an outsized impact: bending resistance scales with the cube of the thickness. By increasing thickness just 44%, aluminum achieves equivalent stiffness, resulting in a 50% weight reduction compared to steel.

2. Strength-Dominated Parts
These parts must withstand high forces without yielding, especially during crash events. Here, material strength becomes critical. While advanced high-strength steels offer excellent properties, so do many aluminum alloys, including within the 6000 and 7000 series. Our general guideline: aluminum can achieve similar performance with a 50–100% increase in thickness, still enabling 30–45% weight savings.

A Sustainable Material for Future Mobility

Aluminum offers more than just lightweighting. It’s a sustainable, infinitely recyclable material that aligns with the automotive industry’s shift toward circularity and carbon reduction. When used strategically, it enhances performance, improves efficiency, and supports both cost and environmental goals.

As electric and hybrid vehicles become more prevalent, aluminum’s role will only grow, helping to balance vehicle performance with energy demands, and enabling smarter, more sustainable mobility.

Sources:
Impact of Vehicle Weight Reduction on Fuel Economy for Various Vehicle Architectures – Ricardo, 2022
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