Application of composite materials in the automotive industry: technologies, advantages and real examples

Body BMW i3 consists of 50% carbon fiber reinforced plastic (CFRP), which reduces the vehicle's weight by 300 kg compared to steel counterparts - while torsional strength increases by 40%. This example demonstrates a key reason why manufacturers are actively implementing composite materials in production models: a combination of low weight, high rigidity and corrosion resistance. However, the use of composites in the automotive industry is not limited to bodies - they are used in suspension, interiors, power structures and even in electric vehicle batteries. Let's look at where exactly and what materials are used, as well as why their share in machine design is growing by 12% annually.

The main driver of the transition to composites is tightening environmental standards (for example, EURO 7 from 2026) that require a reduction in CO₂ emissions. Lightening a car by 100 kg reduces fuel consumption by 0.3–0.6 l/100 km, and in electric vehicles increases the range by 5–10%. But composites also have a downside: high cost (5–10 times more expensive than steel), difficulties with repair and disposal. Below are specific examples of application, comparison of materials and analysis of prospects.

1. Types of composite materials in the automotive industry: from fiberglass to carbon fiber

Composites in the automotive industry are divided into three main groups based on the type of reinforcing fiber and matrix (binder). Their choice depends on the required characteristics: strength, weight, cost and manufacturability.

• 🔹 Fiberglass (GFRP): fiberglass fibers + polymer matrix (epoxy, polyester). It is 3–5 times cheaper than carbon fiber, but the strength is 30–40% lower. Used in bumpers, spoilers, hood covers (Ford Mustang Shelby GT500, Chevrolet Corvette C8).
• 🔹 Carbon fiber reinforced plastic (CFRP): carbon fibers + epoxy resin. Tensile strength is 3000–6000 MPa (for steel it is 400–800 MPa), but the cost is from $20/kg. Used in load-bearing body elements (BMW 7 Series, McLaren 720S).
• 🔹 Aramid fibers (Kevlar): high strength synthetic fibers + polymer. Resistant to shock and vibration, but poorly resistant to UV radiation. Used in armored packages (Mercedes-Benz Guard) and racing helmets.
• 🔹 Hybrid composites: combination of carbon fiber, glass fiber and metal inserts. For example, Audi R8 uses an aluminum space frame with CFRP panels.

It is important to understand that matrix (binder) is no less critical than the fibers. For example, thermoplastic matrices (such as polyamide) allow composites to be processed, but their strength is 15–20% lower than that of thermosets (epoxy). Manufacturers are experimenting with biodegradable matrices based on flax fiber (Volvo tests them in concept Recharge).

2. Body and supporting structures: how composites replace metal

The most common example is monocoque (supporting body) made of carbon fiber, which is used in supercars and premium sedans. For example, McLaren P1 has a full CFRP body weighing 90 kg (for comparison: a steel body of the same size would weigh ~300 kg). But production models are also switching to composites:

• 🚗 BMW i3: CFRP body + aluminum frame. Weight - 1200 kg (250 kg lighter than analogues).
• 🚗 Tesla Model S: aluminum body with CFRP elements in the roof and bumpers.
• 🚗 Lamborghini Aventador: CFRP monocoque + aluminum subframes.

Technologies for the production of bodies from composites:

1. Prepreg: Carbon fiber impregnated with resin is placed in a mold and cured in an autoclave at 180°C. Used in Porsche 911 GT3.
2. RTM (Resin Transfer Molding): Dry fiber is placed in a mold, then resin is injected under pressure. Cheaper than prepreg by 20%, but strength is 10% lower. Applicable in Ford GT.
3. 3D weaving: fibers are woven into a three-dimensional structure, then impregnated with resin. Allows you to create parts of complex shapes without seams (uses Koenigsegg).

A critical issue with composite bodies is repairability. In case of an accident with damage to a CFRP panel, it is often replaced entirely, since restoration costs 70–80% of the cost of a new part. For comparison, a steel element can be straightened or welded for 20–30% of the price.

3. Suspension and chassis: where composites replace metal arms

In suspension, composites are used to reduce unsprung masses (wheels, brakes, levers), which improves handling and comfort. For example, Chevrolet Corvette C8 uses fiberglass wishbones that are 40% lighter than aluminum. Benefits:

• ⚖️ Weight reduction by 30–50% compared to metal.
• 🔧 No corrosion or fatigue cracks.
• 🔄 Possibility to integrate sensors into the structure of the material (for example, to monitor loads).

However, there are also limitations:

⚠️ Attention: Composite suspension arms cannot withstand shock loads when hitting a curb or hole. Unlike steel ones, they do not bend, but rather splinter, which can lead to loss of control. Manufacturers (eg Mercedes-AMG) reinforce them with Kevlar inserts.

Detail	Material	Weight (vs steel)	Model example
wishbone	Fiberglass (GFRP)	–45%	Chevrolet Corvette C8
Anti-roll bar	Carbon fiber reinforced plastic (CFRP)	–60%	Porsche 911 GT3
Suspension springs	Epoxy resin composite	–70%	McLaren Senna
Wheels	Carbon fiber + aluminum	–50%	Koenigsegg Jesko

4. Interior: why composites are replacing plastic and leather

In car interiors, composites are used to lighten the structure and improve the design. For example, Lamborghini Huracán uses CFRP seats weighing 7 kg (vs 15 kg for standard ones), and Tesla Model 3 — a composite center console, which is 30% lighter than plastic.

Key Applications:

• 🪑 Seats: frame made of carbon fiber (weight saving - up to 50%), covering - Alcantara or perforated leather.
• 📱 Dashboard: Composite inserts reduce weight and allow sensor integration.
• 🚪 Door cards: fiberglass with 3D texture like wood or metal (Audi A8).
• 🎵 Acoustic panels: Porous composites absorb noise 20% more effectively than traditional materials.

The advantage of composites in the interior is the ability to create complex ergonomic shapes that cannot be made from metal or wood. For example, the steering wheel Ferrari SF90 Stradale has a CFRP base with integrated control buttons, which reduces weight by 40% compared to its magnesium counterpart.

Myths about composites in the interior

What really?:

- “Composites are brittle and break on impact” → Modern CFRP with elastomeric additives can withstand loads of up to 150 kg/cm² (like aluminum).

- “They look cheap” → 3D weaving and varnishing technologies make it possible to imitate metal, wood or stone (example: Bentley Continental GT).

- “They cannot be painted” → Special UV-resistant paints and films are used (for example, in Porsche Taycan).

5. Electric cars: why composites are critical for batteries

In electric vehicles, composites serve two key functions: they lighten the structure to increase range and protect batteries from damage. For example, battery pack Tesla Model Y has a CFRP housing that:

• 🛡️ Protects cells from punctures in case of an accident (bending strength - 1200 MPa).
• ⚡ Reduces weight by 30% compared to an aluminum body.
• 🔥 Prevents the spread of fire thanks to fire-resistant additives in the matrix.

Composites are also used in:

• 🔋 Battery covers (Jaguar I-Pace - fiberglass with a Kevlar layer).
• ⚡ Terminals and conductors: Copper-coated carbon fiber is 40% lighter than aluminum.
• 🚗 Protective screens: in Rivian R1T The CFRP panel under the battery can withstand a collision with an obstacle 20 cm high.

⚠️ Attention: If the composite battery case is damaged (for example, after an accident), it cannot be repaired - only a complete replacement. Even microcracks can lead to a short circuit and fire. B Tesla Ultrasound scanners are used for diagnostics.

6. Prospects: what awaits composites in the automotive industry by 2030

According to McKinsey, by 2030 the share of composites in the average car will reach 35% (currently ~10%). Main trends:

1. Cheaper production: transition to thermoplastic matrices (cost will decrease by 30%) and automated fiber placement (robots KUKA already used in factories BMW).
2. Recycling: Pyrolysis technologies (resin decomposition at 500°C) are being developed to extract fibers. Volvo plans to use 25% recycled composites by 2026.
3. 4D printing: “shape memory” composites that change geometry when heated (for example, speed-adaptive spoilers).
4. Hybrid solutions: combination of composites with metal in one element (e.g. Audi tests CFRP-clad steel pipes).

Obstacles to mass adoption:

• 💰 High cost of raw materials (carbon fiber - $15-50/kg vs steel - $0.5-2/kg).
• ♻️ Lack of infrastructure for recycling (in the EU only 5% of composites are recycled).
• ⚙️ Lack of qualified repair technicians (certification required, e.g. I-CAR for working with CFRP).

7. How to independently identify composite parts in a car

If you are considering purchasing a vehicle with composite components (e.g. BMW i8 or Alfa Romeo 4C), it is important to be able to identify them. Here are the key signs:

- Weight: A CFRP part is 30-70% lighter than a metal part (take the hood cover or spoiler in your hands).

- Sound: when tapped, carbon fiber produces a high-pitched “metallic” ringing sound, while fiberglass produces a dull thud.

- Structure: layers of fibers are visible on the cut (for CFRP - black, for GFRP - white/yellow).

- Marking: often the manufacturer's logo is applied (for example, TORAY for carbon fiber).-->

To verify the authenticity of CFRP, use a test with a polarizing filter (for example, from sunglasses): when illuminated at an angle of 45°, real CFRP will show rainbow shimmer due to the orientation of the fibers. Counterfeits (painted plastic) will remain matte.

⚠️ Attention: If you are planning on tuning a car with composite parts, keep in mind that:

• 🔧 Mounting holes in CFRP cannot be cut yourself - this disrupts the structure of the material. Use only standard points.
• 🎨 Carbon fiber can only be painted with special UV-resistant paints (for example, PPG or AkzoNobel). Conventional car enamels peel off after 1–2 years.
• 🔥 When sanding CFRP, be sure to use a respirator - carbon fiber dust is carcinogenic.

FAQ: Frequently asked questions about composites in cars

Is it possible to repair a composite bumper after an accident?

Theoretically yes, but economically unfeasible. CFRP repair includes:

1. Removing the damaged layer (with a milling cutter or laser).
2. Laying new layers of prepreg.
3. Autoclave polymerization (120–180°C, 6–8 hours).

The cost of such repairs is 70–90% of the price of a new part. An exception is fiberglass plastic (GFRP), which can be restored using epoxy resin and fiberglass (cost ~40% of a new part).

Why are composite wheel rims not installed on production cars?

Main reasons:

• 💥 Low impact resistance: when hitting a curb, the CFRP disc splits rather than deforms.
• 🔧 Difficulty in balancing: composites have uneven density, which requires precision processing.
• 💰 Price: set of 4 discs Koenigsegg costs ~$20,000 (vs $1000 for forged aluminum).

The exception is racing prototypes (for example, Porsche 919 Hybrid), where weight is more critical than strength.

What composites are used in budget cars?

Mass models (up to $30,000) use:

• 🔹 Fiberglass (GFRP): bumpers, spoilers, trunk lids (Renault Clio, Hyundai i30).
• 🔹 Wood polymer composites (WPC): interior door panels (Volkswagen Polo).
• 🔹 Thermoplastic composites (TPC): decorative trims on the dashboard (Kia Ceed).

Carbon fiber is not used in the budget segment due to its high cost, but some manufacturers (for example, Dacia) are experimenting with recycled CFRP for interior parts.

How do composites affect car insurance?

Insurance companies increase rates for cars with composite parts by 15–30% for the following reasons:

• 💸 High cost of spare parts (for example, a CFRP bumper for BMW M4 costs $3500 vs $800 for a plastic one).
• 🔧 Lack of certified service stations (in Russia, only ~50 centers have equipment for CFRP repair).
• ♻️ Problems with disposal (insurers take environmental risks into account).

The exception is electric vehicles (for example, Tesla), where insurance can be cheaper due to low accident rates.

Is it possible to install composite parts on an old car?

Yes, but with reservations:

• ✅ External tuning: GFRP/CFRP spoilers, diffusers, hoods are compatible with most models (example: Seibon Carbon for Toyota Supra).
• ❌ Load-bearing elements: It is impossible to replace metal side members with composite ones without redesigning the body (the distribution of loads will change).
• ⚠️ Suspension: composite levers require recalculation of the geometry (they are installed only in pairs with original silent blocks).

Before installation, check the parts certification (e.g. ECE R100 for safety elements).