BMW GS 93036 Lightweight Reinforced Thermoplastic (LWRT) for Exterior Use - Requirements and Tests

Developed by BMW, a multinational vehicle manufacturer, the “BMW GS 93036 Lightweight Reinforced Thermoplastic (LWRT) for Exterior Uses - Requirements and Tests” standard describes the requirements and test methods for lightweight reinforced thermoplastics (LWRT) used in automotive exterior components.

Lightweight reinforced thermoplastic (LWRT) materials are lightweight, fiber-reinforced thermoplastic composites that typically contain glass fibers pressed into a thermoplastic matrix. These materials combine low density (for weight savings) with good acoustic damping properties, stiffness, and moldability. This material is commonly used in vehicles for parts such as lower body panels, wheel arch covers, engine bay covers, or other interior and exterior trim elements where reducing mass while maintaining structural integrity and noise reduction is important.

In BMW vehicles, lightweight reinforced thermoplastic (LWRT) material contributes to overall vehicle weight reduction strategies, improved fuel efficiency/electric range, and enhanced noise, vibration, and harshness (NVH) performance.

The BMW GS 93036 standard includes the following:

• Material composition and reinforcement requirements.
• Mechanical properties (e.g., tensile strength, flexural strength, impact strength).
• Environmental resistance (e.g., water absorption/ambient absorption, heat aging, UV exposure, chemical resistance).
• Acoustic performance (sound absorption/insulation properties).
• Other durability tests include, for example, weather resistance, thermal cycling, and adhesion if coated.

According to this standard, tests to ensure that lightweight reinforced thermoplastic (LWRT) materials or components comply with BMW approval requirements are carried out by accredited laboratories.

Typical applications of this standard include:

• External protective shields.
• Wheelbase inner linings.
• Acoustic engine covers or dampers in visible or exposed areas.
• Other lightweight structural coatings exposed to outdoor conditions.

This standard is part of BMW’s broader set of “GS” standards for plastics, coatings and materials. In an era of stricter emissions regulations and the transition to electrification, the BMW GS 93036 standard and similar standards help suppliers provide innovative, lightweight materials that meet BMW’s demands for high performance, durability and quality for outdoor applications.

The basic test categories under this standard are as follows:

• Mechanical properties:
• Tensile strength and elongation.
• Bending strength and modulus.
• Impact resistance (e.g., Charpy or Izod notched/unnotched).

These tests ensure the material can withstand assembly, stone impact, and service loads.

• Environmental resilience and durability:
• Water absorption (environmental absorption): Measures the change in mass/weight after immersion in water or other liquids (e.g., road salt solutions, oils) to assess the risk of swelling or deterioration.
• Thermal aging / thermal stability (long-term exposure to high temperatures).
• Climate/weather resistance simulation (e.g., xenon arc, condensation, thermal cycling).
• Chemical resistance (fuels, oils, cleaners, road salt).
• UV resistance and color fastness (especially if the part is visible or coated)
• Acoustic performance:
• Sound absorption coefficient.
• Sound transmission loss / insulation.

These are critical for underbody and wheel well applications to reduce road and engine noise.

• Other common tests:
• Density and area weight (to verify the claim of lightness)
• Flammability / combustion behavior.
• Dimensional stability after exposure to temperature/humidity.
• Adhesion (if coated or glued).
• Odor or VOC emission tests (more common in indoor features).

The BMW GS 93036 standard is a specific and mandatory standard because it must meet extremely high demands that go beyond general industry standards for exterior applications such as lower body panels, wheel arch covers, engine bay guards, and other exposed components. The main reasons why this standard is necessary are as follows:

• Goals for extreme weight reduction without sacrificing performance: LWRT materials (low-density glass fiber reinforced thermoplastics) offer significant mass savings compared to conventional metal shields or heavier plastics. However, since the exterior parts are exposed to harsh conditions (road debris, water/salt spray, heat, UV rays), they require strict limits on mechanical strength, impact resistance, and dimensional stability.
• Critical acoustic (NVH) requirements: Underbody and wheel arch components significantly influence road and tire noise entering the cabin. LWRT is preferred, partly due to its excellent sound absorption and insulation properties. This standard mandates specific acoustic tests (e.g., sound absorption coefficient, transmission loss) with stringent acceptance criteria.
• Durability in harsh outdoor environments: These components are constantly exposed to the following:
• Submersion in water / high humidity
• Road salt, oils, fuels, and chemicals.
• Extreme temperature fluctuations (from minus 40 degrees to plus 120 degrees or higher)
• UV radiation and weather exposure
• Stone impact and abrasion

This standard includes specific tests such as water/environmental absorption, heat aging, chemical resistance, and weather exposure to prevent swelling, deterioration, delamination, or loss of properties over the vehicle's 10-15 year lifespan.

• Regulatory and sustainability compliance: This standard ensures that innovative, low-density materials continue to meet durability, safety, and NVH targets, while preventing compromises that could negatively impact efficiency gains or customer satisfaction.

In conclusion, without the BMW GS 93036 standard, lightweight exterior LWRT parts may save weight but could compromise noise comfort, long-term durability, or safety.

For many years, our organization, with its competent and experienced team, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services in accordance with the BMW GS 93036 standard.