What Makes the BMW M4 GT4’s Flax Parts Different from Carbon Fiber

The BMW M4 GT4 flax parts set themselves apart from carbon fiber by combining performance with sustainability. BMW, in partnership with Bcomp, uses natural fibre parts such as ampliTex and powerRibs flax-based materials throughout the vehicle.

• The bmw m4 gt4 flax parts replace nearly all CFRP components except the roof, making this car the GT racing leader in natural fibre content.

• Flax composites deliver up to 85% lower greenhouse gas emissions, improved vibration damping, and safer, ductile crash behavior.

• Natural fibre parts support BMW’s goal to cut vehicle life cycle carbon emissions by over 40% by 2030.

Key Takeaways

• BMW’s M4 GT4 uses flax-based natural fiber parts to replace almost all carbon fiber components, making it a leader in sustainable GT racing.

• Flax composites cut greenhouse gas emissions by up to 85% and improve vibration damping and crash safety compared to carbon fiber.

• These natural fiber parts have proven durability and performance through extensive motorsport testing, including tough races like the Nürburgring 24-hour.

• Flax materials offer safer crash behavior by absorbing impact energy without creating sharp debris, enhancing driver safety.

• BMW plans to expand flax composite use to future road cars, supporting a 40% reduction in vehicle CO2 emissions and promoting eco-friendly innovation.

BMW M4 GT4 Flax Parts

Exterior Components

The bmw m4 gt4 flax parts redefine automotive exterior bodywork by replacing traditional carbon fiber with advanced natural fibre parts. Engineers selected flax-based components for the hood, front splitter, doors, trunk, and rear wing of the m4 gt4 race car. These bodywork components benefit from Bcomp’s ampliTex and powerRibs flax fibre reinforced technologies. The powerRibs structure, inspired by leaf veins, maximizes stiffness while minimizing weight. ampliTex provides a visible flax layer, offering a carbon-neutral alternative to conventional coverings.

• The m4 gt4 race car uses flax composites that deliver UV resistance, vibration damping, and high radio transparency—essential for modern sensor integration.

• Flax-based components have proven their durability and performance through seven seasons of motorsport, including Formula E and DTM.

• These materials reduce CO2 emissions by up to 85% compared to carbon fiber, supporting BMW’s sustainability goals.

• The bodywork components meet IATF 16949 automotive quality standards and integrate seamlessly into existing manufacturing processes.

Note: The bmw m4 gt4 flax parts represent the highest proportion of natural fibre parts in any GT series car to date.

Interior Components

Inside the m4 gt4 race car, flax-based components continue to set new standards. The dashboard and center console feature ampliTex flax fabrics combined with powerRibs reinforcement grids. This combination matches the stiffness and weight of traditional carbon fiber, ensuring high mechanical performance. The natural fibre parts offer customizable color, weave, and trim options, allowing unique design signatures that align with BMW’s brand identity.

• Flax fibre reinforced interior panels reduce plastic use by up to 70% and lower CO2 emissions by as much as 90%.

• These bodywork components provide enhanced vibration damping and safer crash behavior, reducing dangerous debris in the event of an accident.

• Extensive motorsport testing confirms the durability and reliability of flax-based components under extreme racing conditions.

• The materials are compatible with thermoset autoclave and Resin Transfer Moulding (RTM), making them suitable for high-volume automotive production.

The bmw m4 gt4 demonstrates how natural fibre parts and flax composites can deliver both sustainability and top-tier performance, setting a benchmark for future automotive innovations.

Flax-Based Composites vs. Carbon Fiber

Material Properties

Natural fiber composites, especially high-performance natural fibre composites, have changed the landscape of automotive engineering. Engineers often compare these materials to carbon fiber, focusing on weight, strength, and vibration damping. Flax-based composites offer a unique balance of properties. While carbon fiber delivers the highest tensile strength and stiffness, flax-based material stands out for its superior vibration damping and sustainability.

A theoretical study using Tsai’s modulus and the Omni Failure Envelope shows that flax composites have lower stiffness and strength than carbon fiber, but they excel in vibration damping. Hybrid designs, which combine flax and carbon fibers, achieve a balance between strength and damping. The following table summarizes the mechanical properties:

High-performance natural fibre composites, such as those used in the BMW M4 GT4, can reduce weight while maintaining adequate strength for motorsport. Flax-based composites also outperform carbon fiber in damping, with up to 150% improvement at low frequencies. This property enhances ride comfort and reduces noise, vibration, and harshness (NVH) inside the car.

Performance in Motorsport

Motorsport teams demand materials that deliver strength, durability, and efficiency. High-performance flax fibre composites have proven their value in racing environments. Flax-based composites maintain strong energy absorption and stiffness under high-speed impacts, which is essential for race cars that experience extreme forces. These materials also show improved wear resistance and lower friction compared to traditional polymers.

Flax-based composites help teams reduce weight without sacrificing durability, which translates to faster lap times and improved fuel efficiency.

Specific energy absorption (SEA) values for flax-based composites reach up to 27 J/g, outperforming other natural fibers and glass fibers. Hybrid composites, which combine carbon and flax, offer a balance of stiffness and ductility. This combination allows engineers to fine-tune the crash response and durability of race car components.

Sustainability remains a key advantage. According to a global market report, flax fiber has a CO2 equivalent footprint that is only 5% of carbon fiber. Life cycle assessments confirm that flax-based biocomposites generate four times less CO2 emissions than carbon fiber composites.

High-performance natural fibre composites not only deliver on the track but also support environmental goals by reducing the carbon footprint of motorsport.

Safety Aspects

Safety is a top priority in motorsport and automotive design. High-performance natural fibre composites, especially those made from flax, offer unique crash behavior compared to carbon fiber. Flax-based composites exhibit a ductile splaying failure mode, which means they absorb impact energy through progressive crushing rather than shattering. This behavior reduces the risk of sharp debris during a crash, enhancing driver safety.

Although carbon fiber composites provide the highest specific energy absorption and stiffness, their brittle failure mode can create dangerous shards. Flax-based composites, on the other hand, offer a safer, more controlled failure pattern. Hybrid designs allow engineers to tailor the crash response, combining the ductility of flax with the strength of carbon fiber.

High-performance natural fibre composites continue to evolve, offering a compelling mix of safety, sustainability, and performance for the next generation of motorsport and road vehicles.

Benefits of Natural Fibre Parts

Environmental Impact

Natural fibre parts deliver significant environmental advantages in automotive applications. Manufacturers who adopt sustainable composite solutions can reduce both waste and emissions, especially when they optimize production with microcellular foam molding. This process alone cuts emissions by about 15% compared to traditional methods. The use of clean energy in manufacturing further lowers the carbon footprint, as electricity consumption accounts for up to 59% of emissions during production.

Life cycle assessments reveal that biocomposite automotive components generate fewer environmental impacts than conventional composites. The use phase of these parts contributes most to their overall impact, followed by manufacturing and disposal. Adding biochar fillers to composites can decrease the global warming potential by up to 3.3 kg CO₂ equivalent per kilogram of material. Flax fibre, when produced as a by-product of seed production, shows a much lower environmental burden than glass fibre, making it a preferred choice for eco-conscious manufacturers.

Manufacturers who prioritize sustainable composite solutions can achieve lower emissions and resource use throughout the vehicle’s life cycle.

End-of-Life and Recycling

Flax-based composites offer improved recyclability compared to traditional materials. Mechanical recycling of these parts retains much of their strength and stiffness, with only a 13% drop in Young’s modulus and a 17% decrease in tensile strength after eight cycles. Substituting glass fibres with flax fibres in polypropylene composites reduces environmental impacts by 10% to 20% across several categories, including global warming and acidification.

• Mechanical recycling stands out as the most environmentally friendly end-of-life method for flax composites.

• Chemical recycling is possible but less sustainable due to higher energy and chemical requirements.

• Incineration with energy recovery is common but does not reclaim material value.

Life cycle assessments confirm that flax fibre composites provide better recyclability and lower environmental impacts than glass fibre alternatives.

Driver Comfort

Natural fibre parts enhance driver comfort in several ways. Flax-based composites improve thermal regulation, keeping skin temperature and moisture at comfortable levels during long drives. These materials also provide excellent acoustic dampening and thermal insulation, which results in a quieter and more pleasant cabin environment.

• Bio-based composites with natural fibers increase flexibility and softness in seating surfaces.

• These materials absorb shocks, which is critical for ergonomic seating.

• The warm tactile feel of natural fibers boosts occupant wellbeing.

Premium automotive brands, including BMW, have adopted these materials for their interiors, demonstrating both practical and comfort benefits.

Future of Flax in BMW M4 GT4 and Beyond

Motorsport Innovation

BMW continues to lead the motorsport industry by expanding the use of natural fibre composites in its racing vehicles. The partnership between BMW Group and Bcomp has lasted several years, resulting in proven performance across multiple racing series, including Formula E, DTM, and GT4. Engineers have validated these materials under extreme race conditions, confirming their durability and suitability for high-stress environments.

• The Škoda Enyaq RS Race demonstrates the impact of biocomposites in motorsport. The car is 316 kg lighter than its production version, thanks to sixteen components made from natural fibres. These parts replace carbon fiber, reducing CO2 emissions by up to 85%.

• Flax-based components maintain the same rigidity and weight benefits as carbon fiber. They also contribute to improved handling, acceleration, and aerodynamics.

• Motorsport teams have adopted these materials for bodywork, interior fittings, and structural parts. The biocomposites have proven their value in vehicles like the Škoda Fabia RS Rally2, where they withstand the rigors of competitive racing.

BMW’s CEO emphasizes that natural fibre composites represent innovative lightweight solutions aligned with the brand’s ethos. The company’s strategy focuses on transitioning from carbon fiber to sustainable alternatives, demonstrating readiness for series production.

Road Car Applications

Automotive manufacturers now recognize the potential of natural fibre composites beyond motorsport. BMW plans to expand the use of these materials to future models, including the next-generation M3 and other series production cars. This move supports the company’s goal of reducing CO2 emissions by 40% in vehicle production.

A comparison between motorsport and automotive implementations highlights the scalability and benefits of these materials:

The Volvo EX30 marks a milestone as the first production vehicle to feature Bcomp’s natural fibre composites in its interior trim. This achievement demonstrates that materials validated in motorsport can transition to mass-market road cars. McLaren’s F1 racing seat, developed with Bcomp, also showcases equivalent strength and stiffness to carbon fiber, with a 75% reduction in CO2 footprint.

BMW’s commitment to these materials signals a broader industry trend. Manufacturers now prioritize sustainability, lightweight construction, and innovative design. The shift from carbon fiber to natural fibres represents a significant step toward a more sustainable automotive future.

BMW’s use of flax-based composites in the M4 GT4 stands out for its innovation and impact.

• The car features the highest proportion of natural fibre parts in GT racing, replacing nearly all carbon fiber components except the roof.

• Flax-based materials deliver up to 40% lower CO₂ emissions during production and reduce greenhouse gases by as much as 85% from cradle to gate.

• Motorsport testing, including the Nürburgring 24-hour race, confirms the durability and safety of these parts.

• Natural fibre components improve vibration damping and enhance crash safety by preventing sharp debris.

BMW’s commitment to these materials signals a shift toward sustainable, high-performance vehicles. Natural fibre composites will shape the future of motorsport and road cars, driving both innovation and environmental responsibility.