What Is the “New Car Smell”? The Technical Truth About Automotive Interior VOCs and Odor Control

When people take delivery of a new car, many consider the distinctive “new car smell” a sign of premium quality. From a materials science perspective, however, this smell is essentially related to the release of volatile organic compounds (VOCs), including benzene, toluene, formaldehyde, acetaldehyde and other substances commonly referred to as the “five benzenes and three aldehydes.” Some of these substances are colorless and odorless, but may pose potential long-term health risks.

Standards and Testing: Two Systems and Three Methods

There are currently two parallel systems for controlling air quality inside vehicles.

• For objective chemical concentration limits, China’s GB/T 27630 specifies upper concentration limits for eight pollutants, including benzene ≤0.11 mg/m³, toluene ≤1.10 mg/m³, xylene ≤1.50 mg/m³, formaldehyde ≤0.10 mg/m³, acetaldehyde ≤0.05 mg/m³, and acrolein ≤0.055 mg/m³. Germany is scheduled to introduce a statutory formaldehyde limit of 0.062 mg/m³ starting in August 2027.

• For subjective odor evaluation, Germany’s VDA 270 standard classifies odors into six levels, from Level 1, meaning no detectable odor, to Level 6, meaning an intolerable odor. A rating of ≤3 is commonly used as the industry acceptance threshold. The 2026 edition of the China Automotive Health Index (C-AHI) adopts the same six-level odor rating system.

• There are three major testing methods: the whole-vehicle environmental chamber method, the bag method, and the climate chamber method. In the whole-vehicle environmental chamber method, the vehicle is maintained under specified temperature conditions before samples of the interior air are collected. This method is widely used in Europe and the United States. In the bag method, individual components are sealed in inert sampling bags and heated at 65°C for two hours before testing, a method commonly used in Japan. The climate chamber method is mainly used for large or irregularly shaped components.

The key point is that the absence of an obvious odor does not necessarily mean that a vehicle meets the relevant standards. Formaldehyde and benzene, for example, can be colorless and odorless, so instrumental testing is essential.

Where Do the Odors Come From? Four Major Material Sources

VOC emissions inside vehicles are highly concentrated in several major material categories.

• Plastic components are the largest source. Instrument panels, door panels and other PC/ABS components may continuously release residual monomers and additives left from the injection molding process. Low-odor PC/ABS materials use vacuum desorption processes to remove residual monomers, reducing odor by approximately 30%–40% and achieving a VDA 270 odor rating of 3.5. Kumho Sunny’s “Sukejing” low-odor material, for example, has a TVOC level of ≤20 μgC/g, significantly lower than the conventional requirements of automotive manufacturers.

• Adhesives are the second major source. Traditional solvent-based adhesives are important sources of formaldehyde and benzene-series compounds. Major automotive manufacturers have increasingly shifted toward water-based adhesives and hot-melt adhesives. In June 2026, the group standard Technical Requirements for Low-Odor Water-Based Spray Adhesives for Automotive Interiors was officially released, specifying an odor rating of ≤3. In leather applications, GAC has adopted PUR adhesives to replace flame lamination, avoiding high-temperature burnt or scorched odors and achieving a final odor intensity of 2.5.

• Seat foam is the third major source. Isocyanate components used in conventional polyurethane foaming are an important source of VOC emissions. The industry is moving toward water-based foaming technologies based on non-isocyanate systems.

• Carpets and damping sheets are the fourth major source. Automotive carpets are increasingly transitioning from PVC to PET tufted fabrics, while asphalt-based damping sheets are gradually being replaced by water-based acrylic and butyl rubber materials.

How Can VOCs Be Controlled? A Full-Chain Approach

VOC control is a systematic process covering materials, manufacturing processes, storage and testing.

• On the manufacturing side, controlling injection molding temperatures to ≤230°C can significantly reduce the formation of aldehydes, while water-based release agents can replace solvent-based alternatives. In 2025, the proportion of companies adopting a dual-mode injection molding process combining vacuum devolatilization and nitrogen protection increased from 31.7% to 48.9%. The average VOC emission level of a single instrument panel decreased to 42.3 μgC/g, representing an 11.6% year-on-year reduction. Online real-time odor monitoring systems were installed on 41.4% of production lines, reducing abnormality detection time from 48 hours to just 15 minutes.

• On the storage side, maintaining temperatures above 25°C and extending the odor dissipation period by 7–14 days can significantly reduce VOC concentrations before vehicle delivery.

• On the testing side, automotive manufacturers commonly establish “golden nose” odor evaluation teams to work alongside instrumental testing. Dongfeng Nissan’s “Golden Nose” system conducts comprehensive screening of 22 odor substances. The N7 model, for example, recorded a formaldehyde concentration of 0.01 mg/m³, only one-tenth of the national standard limit, while the N6 achieved an odor intensity of just 2.5 after exposure to high temperatures. The Luxeed V9 has further adopted MOF-based adsorption and degradation materials, extending VOC management from meeting factory delivery standards to continuous formaldehyde control throughout long-term vehicle use.

Industry Trend: Low VOC Is Becoming an Entry Requirement

In the past, interior air quality was mainly regarded as an added advantage for premium and luxury vehicles. Today, it is increasingly becoming a basic requirement across the automotive industry. Some flagship models have already achieved air-quality performance up to 15 times better than the national standard, while five-star ratings from both C-AHI and C-GCAP are becoming standard elements in new-vehicle marketing.

For CMF and automotive interior engineers, the logic of material selection has fundamentally changed. Color, tactile feel and cost are no longer the only key considerations. Low-VOC performance must increasingly become a veto criterion in material selection.

The rapid transformation of interior interaction and design is also placing higher demands on materials, manufacturing processes and collaboration efficiency throughout the automotive supply chain.