What material are car bodies made from?

Most car bodies are made primarily from steel—especially advanced and ultra-high-strength grades—while aluminum is widely used for hoods, doors, and, in some models, large structural castings; plastics and composites form bumpers and select panels, and carbon fiber appears mostly in high-end or performance vehicles. In practice, modern cars use a mixed-material approach that balances safety, weight, cost, and manufacturability.

The core materials in modern car bodies

Automakers blend materials to meet targets for crash safety, efficiency, cost, and reparability. The following are the main material families used in body structures and exterior panels today.

• Steel (mild, high-strength, AHSS/UHSS, press-hardened): The backbone of most “body-in-white” structures thanks to excellent crash energy management, predictable forming, and cost-effectiveness. Hot-stamped boron steels and tailored blanks provide strength where needed with minimal added mass.
• Aluminum (sheet, extrusions, castings): Cuts weight versus steel. Common for hoods, fenders, doors, liftgates, and increasingly for structural components, including very large “megacastings” in some EVs and SUVs. Requires different joining and repair methods than steel.
• Magnesium: Used sparingly due to cost and corrosion sensitivity, typically for seat frames, instrument panel supports, and occasional inner panels where extreme light weight helps.
• Plastics and polymer composites: Thermoplastics (like PP, TPO, ABS, PC) dominate bumper covers, grilles, and exterior trim; sheet molding compound (SMC) and other composites appear in fenders, roofs, and tailgates on select models for corrosion resistance and styling freedom.
• Carbon fiber–reinforced polymer (CFRP): High stiffness and very low weight make it ideal for supercars and some specialty or performance models (e.g., roofs, hoods, tubs), but cost and repair complexity limit mainstream use.
• Glass fiber composites: Common in niche applications (e.g., Corvette body panels historically) for light weight and design flexibility at lower cost than carbon fiber.

Taken together, these materials let engineers place strength, stiffness, and mass precisely where needed, rather than relying on a single metal for the entire body.

How automakers choose materials

Material selection weighs engineering, business, and regulatory factors. The considerations below explain why most cars mix metals and composites instead of using only one material throughout.

• Weight versus cost: Aluminum and composites save mass to improve efficiency and performance but add material and manufacturing costs; steel remains the value leader.
• Crash performance: Modern steels offer high strength with controlled deformation for occupant protection; aluminum and composites must be engineered differently to manage energy in a crash.
• Manufacturing footprint: Existing press lines, dies, and welding cells favor steel; switching to aluminum or composites can require new tooling and joining technologies.
• Corrosion and durability: Galvanized steels and e-coat treatments protect against rust; aluminum and composites inherently resist corrosion but demand careful galvanic isolation in mixed-metal joints.
• Repairability and insurance costs: Steel is widely repairable; aluminum, composites, and cast structures can require specialized tools or replacement, influencing total cost of ownership.
• Sustainability and recycling: Steel and aluminum have mature, high-rate recycling streams; composite recycling is improving but less established, shaping lifecycle impact decisions.

These trade-offs mean a typical car may use steel for the passenger cell, aluminum for closures, polymers for bumpers, and targeted composites for specific panels.

Where each material shows up on a car

Different body zones place different demands on materials. Here’s where you’re most likely to find each in today’s vehicles.

• Body-in-white (BIW) structure: Predominantly steel (including AHSS, UHSS, and hot-stamped parts). Some vehicles integrate aluminum extrusions, sheet reinforcements, or large aluminum castings at the front and rear.
• Exterior panels: Bumpers are almost universally plastic. Hoods, roofs, doors, and liftgates can be steel or aluminum depending on model and trim; select models use composite roofs or fenders.
• Closures and lids: Aluminum is common to reduce high-mounted mass (hoods, trunk/liftgates, doors). Steel remains prevalent in cost-sensitive segments.
• Chassis-adjacent structures: Shock towers, crossmembers, and subframes can be steel or aluminum; premium/performance models often favor aluminum.
• EV battery enclosures and floors: Often aluminum (sheet/extrusions) for weight and thermal behavior; some use steel for impact robustness, while composites are emerging to meet corrosion and weight targets.

The net result is a tailored material map: steel where crash loads are critical, lighter materials where mass savings most benefit handling and range.

Joining and manufacturing that enable mixed materials

Combining metals and composites depends on fabrication and joining technologies that preserve strength and manage corrosion. The tools and processes below make modern bodies possible.

• Resistance spot welding and laser welding: Mainstays for steel BIWs, with laser welding supporting long, stiff seams.
• Structural adhesives: Increase stiffness, distribute loads, and isolate dissimilar metals to reduce galvanic corrosion; widely paired with mechanical fasteners.
• Self-piercing rivets (SPR) and flow-drill screws: Key for aluminum and mixed-metal stacks where spot welding is impractical.
• Friction stir welding: Solid-state process used for some aluminum joins, including battery enclosures.
• Hot stamping and tailored blanks: Create ultra-strong, precisely reinforced steel parts for pillars, rockers, and roof rails.
• Hydroforming and roll forming: Produce complex, high-strength sections with good dimensional control.
• Compression molding (SMC) and injection molding: Common for composite and plastic exterior panels with integrated features.
• Large aluminum die castings (“megacastings”/“gigacastings”): Combine dozens of stamped parts into a single rear or front structure on some EVs, simplifying assembly and cutting weight; now being explored by multiple global automakers.

These processes let automakers place the right material in the right spot and assemble it reliably at scale.

Trends shaping 2024–2025 models

Material strategies continue to evolve with electrification, stricter safety standards, and cost pressure. Current industry trends include:

• Multi-material bodies as the default: Even budget models combine steels with aluminum closures and polymer fascias to balance mass and cost.
• More advanced steels: Automakers keep increasing AHSS/UHSS content to meet crash goals without major cost or tooling upheaval.
• Expansion of large aluminum castings: Front/rear “megacastings” in select EVs reduce parts count and simplify underbody structures; additional brands are piloting and localizing the approach.
• Lightweight closures and roofs: Aluminum and composite roofs/doors proliferate to lower the center of gravity and improve efficiency.
• EV-specific structures: Battery enclosures and underfloor reinforcements favor aluminum and high-strength steel; some integrate the pack as a stressed member in the body.
• Recycling and low-CO₂ materials: Wider use of recycled-content aluminum and steel, along with coatings and sealants to extend life and reduce environmental impact.
• Repairability focus: Insurers and regulators are pressing for designs that limit total-loss rates from expensive-to-repair materials or castings, influencing where and how new materials are used.

The net effect is not a single “best” material, but smarter combinations and manufacturing choices tailored to each vehicle’s mission and price point.

Summary

Car bodies today are predominantly steel—especially advanced high-strength grades—for the main safety cell and structure. Aluminum is widely used for closures and increasingly for structural castings, plastics and composites form bumpers and selected panels, and carbon fiber appears mainly in performance and luxury segments. Most vehicles blend these materials, using modern joining and forming methods to hit targets for safety, efficiency, durability, cost, and repairability.

What is the most common vehicle construction material?

Steel (Iron Ore)
Steel is produced from iron ore and is traditionally widely used in auto manufacturing. On average, 900 kilograms of steel are used in every car. Steel is used to construct a car’s chassis and body, including the roof, body, door panels, and the beams between doors.

What material are most car bodies made of?

Car bodies today are most commonly made of steel and aluminum, with steel remaining a cost-effective choice for mass-produced vehicles. Aluminum is increasingly used for its lightweight properties, which improve fuel efficiency, particularly in larger vehicles. For higher-performance or more expensive sports cars, bodies can be made from strong but costly carbon fiber. Additionally, lightweight magnesium alloys are used for specific components, and various types of plastic are used for other parts like front and rear panels. 
Key materials and their uses:

• Steel: Opens in new tabRemains the traditional and most widely used material due to its strength, durability, and low cost. 
• Aluminum: Opens in new tabBecoming the material of choice for its lighter weight and corrosion resistance, used in components like hoods and liftgates. 
• Carbon Fiber: Opens in new tabA very strong and lightweight material, but its high cost restricts its use to high-end or specialty vehicles. 
• Plastic: Opens in new tabUsed extensively for various parts, including front and rear panels and other trims. 
• Magnesium Alloys: Opens in new tabLightweight magnesium is increasingly used for certain body components. 

Why the different materials are chosen:

• Cost: Steel is the most economical choice for most vehicles. 
• Weight: Aluminum and carbon fiber help reduce vehicle weight, leading to better fuel efficiency and performance. 
• Strength and Safety: All materials are chosen to meet strict safety standards, with different steels and other materials providing varying levels of crash protection. 
• Corrosion Resistance: Aluminum and certain steel treatments are important for protecting against rust. 

When did cars stop being made of metal?

Cars never completely stopped being made of metal; rather, metal became a material alongside plastic, aluminum, and other materials, rather than the sole primary component. While the industry shifted toward mass production of steel-bodied cars in the early 20th century, the use of other materials like plastic increased significantly from the mid-20th century onwards to reduce weight, improve fuel efficiency, and meet emissions standards.
 
History of Metal in Cars

• Early 20th Century: The introduction of the first all-steel-bodied automobile in 1914 by Dodge marked a major shift, with steel bodies becoming the standard by the late 1930s. 
• Mid-20th Century: Steel continued to be the primary material for car chassis and bodies through the early 1970s and beyond. 
• Late 20th Century: Despite the prevalence of steel, there was also a shift towards using more aluminum for bodies to improve fuel economy. 
• Modern Cars: Today, cars are made from a combination of materials, including steel, plastic, aluminum, rubber, and glass. 

Reasons for Material Diversification 

• Weight Reduction: The use of plastic and aluminum in vehicles helps to reduce overall weight.
• Fuel Efficiency: Lighter vehicles require less fuel, improving fuel economy.
• Emissions Standards: Reducing fuel consumption also leads to lower emissions, helping manufacturers meet stricter environmental regulations.

What were the bodies of cars in 2025 made of?

The study finds that every leading automaker will have numerous aluminum body and closure programs by 2025. As the material mix for body and closure parts continues to change in the years to come, use of aluminum sheet for vehicle bodies will increase to 4 billion pounds by 2025, from 200 million pounds in 2012.