What Are Car Bodies Made Of Now?

Today’s car bodies are multi‑material structures: mostly advanced steels for the safety shell, increasing amounts of aluminum for panels, castings and battery enclosures (especially in EVs), plus plastics and composites for exterior skins and select structural parts; high-end performance models may add carbon fiber. Automakers mix materials to balance safety, weight, cost, manufacturing speed, repairability and sustainability, so the exact recipe varies by vehicle segment and brand.

From All-Steel Shells to Multi‑Material Structures

For decades, the “body-in-white” (the welded body shell before paint) was predominantly stamped mild steel. Modern vehicles still rely heavily on steel, but now blend multiple grades of high- and ultra-high-strength steels with aluminum sheets, extrusions and castings, polymer composites, and, at the top end, carbon fiber. The shift is driven by stricter safety and efficiency targets, the packaging needs of electric vehicles, and manufacturing innovations that let unlike materials be joined reliably at scale.

The Core Materials, and Where You’ll Find Them

The following list outlines the primary materials used in contemporary car bodies and the typical places you’ll encounter each in production vehicles.

• Steels (mild, high-strength, advanced high-strength/AHSS, press-hardened/UHSS): Form the crash “cage” and much of the body structure—A/B/C pillars, roof rails, floor crossmembers, rockers, and door rings. Hot-stamped parts can exceed 1,500 MPa tensile strength, enabling thinner sections with high crash performance. Most steel body panels are galvanized (GI/GA) for corrosion resistance.
• Aluminum (sheet, extrusions, die castings and “mega/giag-castings”): Common for hoods, liftgates, fenders and doors on many models; widely used in bumper beams, crash boxes and subframes. EVs frequently use aluminum extrusions and castings for battery enclosures and underbody structures. Some automakers employ large aluminum castings in front and rear body sections to reduce part count and weight.
• Magnesium (die castings): Targeted use in low-weight components such as instrument-panel cross-car beams, seat frames or steering-wheel cores. Exterior structural use is limited due to cost, corrosion and joining challenges.
• Plastics and polymer composites (PP/TPO, ABS, PC, SMC): Bumper fascias, grilles, underbody aero shields, wheel-arch liners and some fenders are thermoplastics. Sheet-molding compound (SMC) composite panels appear on certain models (for example, pickup beds and sports cars). Plastics reduce weight, resist minor dents, and integrate complex styling features.
• Carbon-fiber reinforced polymer (CFRP): Predominantly in supercars and some premium trims—full monocoques on exotics, and selective parts like roofs, hoods, and reinforcement panels on performance variants. Used sparingly in mainstream vehicles due to cost and repair complexity.
• Glass and glazing: Laminated glass for windshields (often acoustic), tempered for side/rear windows; large panoramic roofs pair glass with steel or aluminum frames and crossmembers.

Taken together, steel remains the dominant mass in most body shells, aluminum is rising—especially in closures, castings and EV underbodies—while plastics/composites are used where they make sense for styling, aerodynamics and corrosion resistance; carbon fiber is still a niche, high-performance choice.

Why These Materials? The Trade‑offs

Automakers choose materials based on a balance of performance, manufacturability, sustainability and cost. The points below summarize the key drivers behind today’s mixes.

• Weight vs. cost: AHSS delivers high strength at relatively low cost; aluminum cuts mass significantly at higher material and energy cost; CFRP is lightest but pricey, tooling-intensive and slow to process at volume.
• Safety and crash management: Ultra-high-strength steel builds a rigid safety cell, while controlled-crush aluminum extrusions and stampings manage energy in front/rear impacts. Door rings and pillars often use hot-stamped steel for intrusion resistance.
• Manufacturing speed and complexity: Stamping steel remains fast and economical; aluminum needs different forming, joining and surface treatments. Large aluminum castings reduce part count and welding, but require expensive die-casting machines and raise repair considerations.
• Corrosion and durability: Galvanized steel and e-coat primer are standard; mixed-material joints must be isolated to avoid galvanic corrosion, often using adhesives, sealers and coatings.
• Sustainability: Recycled aluminum and higher recycled content in steels are increasing; “low-carbon” steel made with electric arc furnaces and renewable power is entering supply chains. Automakers track lifecycle impacts, not just curb weight.
• Repairability and insurance: Many AHSS/UHSS parts are replace-only (not straightened). Aluminum panels and structures demand specialized tools and isolation from steel work. Plastic fascias with embedded ADAS sensors can be expensive to replace and recalibrate. Large castings may simplify assembly but can mean replacing a big structural section after a crash.

The net effect is that no single material “wins” everywhere—engineers deploy each where it brings the best mix of strength, mass, cost, sustainability and serviceability for the intended vehicle and market.

EVs Are Reshaping the Underbody

Electric vehicles introduce a flat battery “skateboard” that changes the body’s structure. Many packs use aluminum extrusions and plates for their tray and side rails, sometimes with steel reinforcements in high-load paths. Some automakers integrate the pack structurally with the body, aided by large aluminum castings front and rear to create a stiff, crashworthy floor. Composite covers and shields can provide impact and thermal protection while controlling weight and noise.

Examples by Segment

The following examples illustrate how material mixes typically differ by vehicle type; exact percentages vary by model and generation.

• Affordable compact/midsize cars: Predominantly steel BIW with a growing share of AHSS/UHSS; aluminum hoods or fenders on some models; plastic fascias and underbody panels for aero.
• Pickups and large SUVs: High-strength steel frames; aluminum for closures and, in some cases, full outer bodies; composite pickup beds or bedliners on select models; robust plastic or metal skid plates and shields.
• Mainstream EVs: Aluminum-intensive battery enclosures and crash rails; steel safety cages; plastic aero shields; some platforms adopt large aluminum rear/front castings to reduce complexity.
• Performance and luxury: More aluminum in spaceframes and closures; selective CFRP parts (roofs, trunk lids, monocoques on exotics); targeted magnesium castings for weight-critical components.

These patterns are general: even within a segment, material strategies differ based on brand priorities, platform age, and supplier ecosystems.

How Parts Are Joined

Mixing metals and composites demands varied joining methods; the choice affects both factory throughput and downstream repair techniques.

• Resistance spot welding and laser welding: Mainstay for steel stampings; high speed and automation-friendly.
• Structural adhesives: Ubiquitous across metals and composites to boost stiffness, seal joints and mitigate galvanic corrosion; often combined with mechanical fastening.
• Self-piercing rivets, flow-drill screws and clinching: Enable joining aluminum-to-aluminum and mixed-metal stacks where spot welding isn’t feasible.
• Friction stir welding and brazing: Used on aluminum extrusions, battery trays and heat-sensitive assemblies for strong, consistent seams.
• Composite bonding and inserts: Adhesive bonding, co-curing, and mechanical inserts attach CFRP/SMC parts to metal structures.

These techniques are part of why multi-material bodies are now routine—and why certified repair procedures and tools matter more than ever.

What It Means for Buyers

Material choices influence how a vehicle drives, how safe and quiet it feels, its fuel or energy use, and what collision repair might cost. Aluminum closures can resist corrosion and save weight; AHSS cages contribute to high crash ratings; plastic fascias and aero panels help efficiency but can house sensors that add to repair bills. For EVs, aluminum-heavy underbodies and battery enclosures are common, so ask about manufacturer repair networks and insurance implications if you’re shopping.

Bottom Line

Modern car bodies are engineered mosaics: steel for the protective skeleton, aluminum for weight- and package-critical structures and panels, plastics/composites for form and function, and carbon fiber where performance budgets allow. The exact mix is tuned to the mission—commuter car, family SUV, work truck or high-performance EV—and will keep evolving as automakers chase safety, efficiency and sustainability goals.

Summary

Most cars today use a multi-material body: advanced steels remain the backbone, aluminum is widespread in panels, castings and EV battery structures, plastics/composites handle exterior skins and aero, and carbon fiber appears mainly in premium performance models. The blend reflects trade-offs among safety, weight, cost, manufacturing and repair, with EV packaging accelerating aluminum usage and new casting techniques.

When did cars go from metal to plastic?

Plastics first saw use in car interiors in the 1920s. First exterior use was in the late ’40s when metal parts coated with simulated wood-grain vinyl replaced real wood veneers on outside sheet metal for the classic “woody” look. By the 1960s, vinyl took over vehicle interiors.

Are modern car bodies galvanised?

Nowadays, the use of zinc-coated bodies for automobiles is standard procedure in auto manufacturing. The ‘body-in-white’ of a car makes up about 80% of the body, all using galvanized steel.

What are car bodies made of today?

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. 

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.