What Are Cars Made Of? The Materials Behind Modern Automobiles

Cars are not made of a single material: modern vehicles are multi‑material products combining steel and iron, aluminum (and some magnesium), plastics and elastomers, fiber‑reinforced composites, glass, rubber, electronic materials, and—on electric vehicles—battery chemistries such as NMC, NCA, or LFP. The exact mix varies by vehicle type, cost target, safety and efficiency goals, and manufacturing strategy.

The Structural Backbone: Metals

Metals form the core structure of most cars. Automakers balance cost, weight, crash safety, and manufacturability by blending advanced steels with lightweight metals like aluminum.

Steels and Irons

Steel remains the dominant material in the “body‑in‑white” (the welded shell), thanks to its strength, crash performance, and affordability. Automakers increasingly use advanced high‑strength steel (AHSS)—including dual‑phase (DP), TRIP, martensitic, and press‑hardened grades—to reduce thickness and weight while meeting safety standards. Cast iron still appears in certain powertrain components, though its share has shrunk with engine downsizing and electrification.

The most common places you’ll find steel and iron include the following areas of a typical vehicle’s structure and hardware.

• Body‑in‑white: pillars, rails, roof bows, crossmembers, rockers (often AHSS and press‑hardened steel)
• Crash structures: front and rear crash boxes, load paths, door intrusion beams
• Chassis: subframes, suspension arms and links (in steel or aluminum depending on vehicle), fasteners
• Powertrain (ICE): engine blocks/liners (steel/iron or aluminum blocks with iron liners), crankshafts, gears

Together, these steel and iron components typically make up the majority of a vehicle’s mass, though the share has been trending lower as aluminum usage rises and EVs consolidate structures differently.

Aluminum and Magnesium

Aluminum’s high strength‑to‑weight ratio and corrosion resistance make it attractive for closures (hoods, doors, tailgates), castings (motor housings, subframes), and increasingly for large structural castings. “Gigacasting” of rear and front underbody sections—pioneered at scale by Tesla and now being explored or adopted by several global automakers—reduces parts count and welds while saving mass. Magnesium, even lighter than aluminum, appears in smaller parts like steering wheel frames, seat structures, and instrument panel carriers, but its use is limited by cost and corrosion challenges.

Below are common aluminum applications and why manufacturers choose them.

• Closures and exterior panels: weight savings for efficiency and handling
• Casting-intensive parts: motor/inverter housings, subframes, shock towers, large underbody castings
• Wheels and heat exchangers: thermal performance and durability
• Battery pack enclosures (EVs): stiffness, crash energy absorption, corrosion resistance

Aluminum content has climbed steadily—particularly in EVs and premium vehicles—because it offers substantial weight savings that translate into range and efficiency gains.

Composites and Polymers

Plastics, elastomers, and fiber‑reinforced composites are critical for weight reduction, design flexibility, aerodynamics, and cost control. They also enable complex shapes and integrated features.

Plastics and Elastomers

Thermoplastics and thermosets appear throughout a vehicle, from bumpers to dashboards. Elastomers provide sealing, NVH (noise, vibration, harshness) control, and flexibility under load and temperature changes.

These are the polymers and rubbers most commonly found in modern cars and why they are used.

• PP (polypropylene): bumpers, interior trim, under‑trays; light and inexpensive
• ABS/PC-ABS: interior panels and consoles; toughness and surface finish
• PA (nylon) and POM (acetal): under‑hood components, gears, connectors; heat/chemical resistance
• PC (polycarbonate): headlamp lenses, light covers; clarity and impact resistance
• PU (polyurethane) foams: seats, acoustic foams; comfort and NVH
• PVC and TPOs: wire insulation, sealings, skins; flexibility and durability
• EPDM, NBR, silicone rubbers: weatherstrips, hoses, seals; temperature and fluid resistance

Together, these materials cut weight, enable complex geometries, and improve cabin comfort and durability, though end‑of‑life recycling for mixed plastics remains a challenge.

Fiber‑Reinforced Composites

Composites combine fibers and resin to deliver high stiffness and low weight. Carbon‑fiber reinforced polymer (CFRP) shows up in high‑end parts like roofs, hoods, and structural elements on performance vehicles, while glass‑fiber composites (GFRP) and sheet‑molding compound (SMC) are common in exterior panels and load floors. Natural fiber composites (e.g., hemp, kenaf, flax) increasingly reinforce interior panels to cut weight and improve sustainability.

Examples illustrate where composites make sense in today’s cars.

• CFRP: roof panels, driveshafts, seat shells, select structural reinforcements in high‑performance models
• GFRP/SMC: trunk lids, pickup beds, under‑body aero panels, battery pack covers
• Natural fiber composites: door cards, trunk trims, parcel shelves, center consoles

While composites are expensive versus metals, targeted use delivers lightweighting and stiffness where it matters most, with growing interest in bio‑based fibers and recyclability improvements.

Glass and Glazing

Automotive glazing uses safety glass engineered for impact and clarity. Windscreens are laminated—two layers of glass with a plastic interlayer—to prevent shattering; side and rear windows are usually tempered for strength. Acoustic and solar‑control laminates, hydrophobic coatings, and head‑up display (HUD) compatible interlayers are increasingly common. Polycarbonate remains for headlamp lenses and certain roof applications but is typically not used for front windshields on road cars due to abrasion and regulatory constraints.

Electrical and Battery Materials

Electrification has pushed material diversification in wiring, motors, power electronics, and high‑voltage energy storage. Copper remains crucial for conductors, though aluminum is used in larger cables to save weight. Power electronics rely on silicon and, increasingly, silicon carbide (SiC) for higher efficiency. Permanent‑magnet motors often use neodymium‑iron‑boron (NdFeB) magnets with dysprosium or terbium for high‑temperature stability, while some manufacturers avoid rare earths via induction or wound‑field designs.

Key EV battery and electrical materials include the items below.

• Battery cathodes: NMC/NCA (nickel, manganese, cobalt), or LFP (lithium iron phosphate) for cost and longevity
• Anodes: graphite with growing use of silicon blends for higher energy density
• Electrolytes/separators: organic solvents and polyolefin separators; solid‑state cells are under development
• Conductors and busbars: copper and aluminum in wiring harnesses and battery packs
• Power electronics: Si and SiC devices, substrates, and thermal interface materials
• Thermal management: coolants, heat spreaders, gap fillers, phase‑change materials
• Pack structures: aluminum or steel casings, foams, fire‑protection barriers

The industry has shifted many mainstream models to LFP packs for value and durability, while high‑performance and long‑range variants still favor nickel‑rich chemistries; solid‑state and sodium‑ion cells are progressing through pilot and early commercialization phases.

Interiors, Finishes, and Fluids

Inside the cabin, comfort and aesthetics drive a wide mix of materials—from textiles to foams—while coatings and adhesives protect the exterior and enable robust assemblies. Fluids support cooling, lubrication, and climate control.

Common interior and finishing materials appear across the following categories.

• Upholstery: woven and knit textiles, microfiber, leather and synthetic leather, recycled PET fabrics
• Foams and fillers: polyurethane seat foams, acoustic foams, felt and recycled fiber mats
• Adhesives and sealers: structural epoxies, urethanes for glazing, seam sealers for corrosion protection
• Paint systems: e‑coat (electrocoat primer), primer, basecoat, clearcoat; increasingly waterborne and low‑VOC
• Fluids: engine/transmission oils (less or different in EVs), coolants, brake fluid, and low‑GWP refrigerants like R‑1234yf

These materials collectively shape tactile quality, noise isolation, corrosion resistance, and long‑term durability, with growing emphasis on low‑emission finishes and recycled content.

Sustainability and Recyclability

End‑of‑life vehicle regulations and corporate climate targets are pushing higher recycled content and better recovery. Steel and aluminum are highly recyclable and often contain significant recycled content. Plastics recycling is improving via better sorting, chemical recycling pilots, and design‑for‑disassembly, though it still lags metals. Battery recycling—through hydrometallurgical and pyrometallurgical processes—is scaling to recover lithium, nickel, cobalt, and other materials, aided by new regulations in the EU and incentives in North America. Interior components increasingly incorporate recycled polymers and natural fibers.

How Materials Vary by Vehicle Type

Material choices depend on performance targets, segment, and cost. Several common patterns illustrate the trade‑offs across the market.

• Economy cars: higher steel share, targeted plastics for cost and weight, minimal composites
• Luxury and performance vehicles: more aluminum and CFRP, acoustic laminated glass, premium interior materials
• Pickups and SUVs: robust frames (often steel), aluminum panels/closures on some models, durable interior surfaces
• EVs: increased aluminum in body and battery enclosures, high copper/aluminum content in wiring and busbars, battery‑specific materials

These choices reflect a balance between affordability, efficiency, safety, and brand positioning, with EV architectures particularly influencing metal and thermal‑management strategies.

Key Trends in 2025

Automotive material strategies continue to evolve rapidly as regulations, electrification, and manufacturing innovation reshape designs.

• Broader use of third‑generation AHSS for crash performance with thinner gauges
• Expansion of large aluminum castings (“gigacastings”) to reduce parts count and assembly time
• Mainstream adoption of LFP batteries in value and fleet EVs; nickel‑rich chemistries for premium range
• Sodium‑ion batteries entering early market trials for cost‑sensitive, short‑range vehicles
• Silicon‑carbide power electronics for higher efficiency in inverters and fast chargers
• More recycled and bio‑based polymers in interiors, plus design‑for‑recycling initiatives
• Increased use of acoustic laminated glass and advanced coatings for comfort and efficiency

Taken together, these trends point to lighter, more efficient vehicles with a higher share of recyclable and lower‑impact materials, especially as EV volumes grow.

Summary

A car is a carefully engineered mix of materials: steels and irons for structure and crash performance; aluminum and some magnesium for lightweighting and large castings; plastics, elastomers, and composites for form, function, and mass reduction; safety glass for visibility and protection; and, in EVs, specialized electrical and battery materials. The proportions depend on vehicle type and cost, but the trajectory is clear—more advanced steels, more aluminum, smarter composites, and a growing emphasis on recyclable and lower‑carbon materials across the entire vehicle lifecycle.

Is a car metal or plastic?

In cars, steel is used to create the underlying chassis or cage beneath the body that forms the skeleton of the vehicle and protects you in the event of a crash. Door beams, roofs and even body panels created during auto manufacturing are made of steel on most cars today.

What material is the exterior of a car?

Car exteriors are primarily made of steel, but modern vehicles also incorporate aluminum, plastic, and carbon fiber to balance weight, strength, and cost. Steel is a traditional choice for its strength and affordability, while aluminum offers a lighter, rust-resistant alternative. Plastic is common for non-structural parts like bumpers, and carbon fiber is a high-tech, expensive option for lightweighting performance vehicles.
 
Main Exterior Materials

• Steel: Opens in new tabThe most common and traditional material, steel provides excellent strength and collision resistance at a lower cost, making it ideal for the structural chassis and body panels of mass-produced vehicles. 
• Aluminum: Opens in new tabUsed in luxury and performance cars, aluminum is significantly lighter than steel and resistant to rust, which helps improve fuel efficiency and performance, according to Quora users. 
• Plastic: Opens in new tabFound in non-structural components such as bumpers, door handles, and trim, plastic is chosen for its light weight, flexibility, and ability to be molded into complex shapes. 
• Carbon Fiber: Opens in new tabA high-end material used in supercars and advanced models, carbon fiber is exceptionally strong and very lightweight, contributing to improved performance and reduced overall vehicle mass. 

Other Materials 

• Glass: Used for windows and windshields.
• Paint and Clear Coat: The outermost layers that provide protection and a finished appearance.
• Rubber: Used for seals, weather stripping, and other components.

What material are cars made of?

Steel, rubber, plastics, and aluminum are the four most common commodities found in cars. The auto industry relies heavily on petroleum products, not just for gasoline for autos with internal combustion engines (ICE), but for synthesizing plastics and other synthetic materials.

What material is a car motor made of?

An aluminum internal combustion engine is an internal combustion engine made mostly from aluminum metal alloys. Many internal combustion engines use cast iron and steel extensively for their strength and low cost. Aluminum offers lighter weight at the expense of strength, hardness and often cost.