FMVSS 302: Flammability Testing for Vehicle Interior Materials
When you step into a vehicle, whether it is a passenger car, a military truck or a forklift, you are surrounded by materials that can burn under the wrong conditions. FMVSS 302, Federal Motor Vehicle Safety Standard No. 302 (49 CFR 571.302), is the US standard that limits how fast those interior materials may burn.
This regulation has been in place for decades, yet it still appears in technical specifications, tenders and procurement contracts. Knowing what it requires, and what it does not, helps buyers and safety managers make better decisions.
What is FMVSS 302?
FMVSS 302 is specifically about the flammability of interior materials. The rule limits how quickly a material can burn when exposed to a small flame: the burn rate must not exceed 102 millimetres per minute. By slowing the spread of a fire, the regulation ensures that materials inside the vehicle give occupants enough time to escape.
The scope covers seat cushions, seat backs, seat belts, headlining, floor coverings, sun visors, trim panels, armrests, head restraints and the other occupant compartment components listed in clause S4.1. Any part of a listed material that lies within 13 mm of the occupant compartment air space must meet the burn rate requirement.
The stated purpose (S2) is to reduce deaths and injuries from vehicle fires, especially those that start inside the vehicle from sources such as matches or cigarettes. That is why the test uses a small flame rather than a fuel fire.
NHTSA published the FMVSS 302 standard on 2 December 1971 (36 FR 22902). It was last amended in 1998, when the text was converted to metric units, and the eCFR shows no change since. In January 2025 Consumer Reports, the Green Science Policy Institute and the International Association of Fire Fighters petitioned NHTSA to replace the open flame test with a smoulder test.
As of March 2026 the petitioners reported no substantive response from the agency, so the 1971 test method remains the requirement.
How the FMVSS 302 Test Works
The test method is deliberately simple, which is one reason it has remained in use for decades.
| Step | Detail |
|---|---|
| Sample preparation | A strip 102 mm wide and 356 mm long is cut in the direction that gives the most adverse result, at most 13 mm thick, and conditioned for 24 hours at 21 °C and 50% relative humidity. |
| Positioning | The strip is held in a U-shaped metal frame and placed horizontally in a metal test cabinet, with the surface that faces the occupant compartment pointing down. |
| Ignition | A Bunsen burner flame 38 mm high is applied to the open end for 15 seconds. |
| Self-extinguishing check | Timing starts when the flame reaches a point 38 mm from the open end. If the flame goes out before that point, no burn rate is measured and the material passes. |
| Burn rate calculation | If the flame continues, the burn rate is calculated as B = 60 × D/T (D in mm, T in seconds) and must be at or below 102 mm per minute to pass. |
The horizontal orientation and defined flame size produce consistent, reproducible results that allow material comparisons across suppliers and test facilities. The pass criterion itself sits in clause S4.3, which also lets a material that goes out quickly comply.
FMVSS 302 Requirements: Where the Standard Applies
- Civilian vehicles: All passenger cars, multipurpose passenger vehicles, trucks and buses sold in the US must use interior materials meeting FMVSS 302 (clause S3); trailers are not covered. This covers original equipment and, in practice, is expected of aftermarket replacement materials in the same locations, since US law bars repair businesses from knowingly making a compliant element inoperative.
- Industrial and construction vehicles: Forklifts, construction machines and mining equipment operating in high fire risk environments often use FMVSS 302 as a baseline compliance reference even where it is not legally mandated. The matching test method, ISO 3795, names tractors and machinery for agriculture and forestry in its own title.
- Military and defence vehicles: FMVSS 302 can appear as a baseline requirement in military vehicle specifications, with more demanding military standards applied on top. Environmental and durability testing of the same vehicle components is set by MIL-STD-810.
- Aircraft: FMVSS 302 is referenced in some aviation procurement, particularly for ground support vehicles. Aircraft cabins themselves fall under aviation rules, such as 14 CFR 25.853 for the compartment interiors of transport category aeroplanes.
Interior Lights and Other Cab Components
The S4.1 component list is closed. In a 1996 interpretation, NHTSA’s Chief Counsel stated that any material not on the list is not subject to the standard, and the catch-all at the end of S4.1 reaches only other interior materials designed to absorb energy on contact with occupants in a crash, such as padding.
Lamp housings and lenses are not named, so an interior lamp is not a listed component by default. A vehicle manufacturer or defence programme can still require it, or another fire test, in its own specification for cab equipment.
Our interior vehicle light, for example, uses an acrylic lens and a polycarbonate housing, and its product page states no flammability rating. Where a specification names FMVSS 302, UL 94 or another fire test for interior lighting, raise it at the enquiry stage so the requirement can be checked against the materials.
Exterior lamps are a separate matter. On US road vehicles they fall under FMVSS 108, and DOT vs ECE vs SAE sets out how the US, UNECE and SAE rules divide that work.
FMVSS 302 vs Other Flammability Standards
| Standard | Scope | Test orientation | Limit |
|---|---|---|---|
| FMVSS 302 | US cars, trucks, buses and MPV interiors | Horizontal | 102 mm/min |
| ISO 3795 | Road vehicles, tractors, farm and forestry machinery | Horizontal | Set by the citing document |
| ECE R118 | Bus and coach interiors (M3, Class II and III) | Horizontal and vertical, plus melting | 100 mm/min |
| UL 94 | Plastic parts in devices and appliances | Horizontal (HB) and vertical (V) | HB: 40 or 75 mm/min |
FMVSS 302 and UL 94 are often compared in procurement. The key difference is scope: FMVSS 302 is specific to vehicle interior materials and is tested horizontally, while UL 94 rates plastics for parts in devices and appliances in horizontal and vertical tests. A material can comply with both standards, but compliance with one does not automatically imply compliance with the other.
For cross-regional sourcing, passing FMVSS 302 often supports compliance under ISO 3795 given the similar test methodology, but separate test reports are typically still needed. Bus and coach programmes in UNECE markets add the vertical and melting tests of ECE R118.
FMVSS 302 in Electric and Hybrid Vehicles
Battery-related fire incidents in electric and hybrid vehicles present different hazards from a burning seat cushion. But if a battery fire spreads into the cabin, the time occupants have to escape depends directly on whether interior materials meet FMVSS 302.
The standard does not test for battery fires. Its 15 second Bunsen flame measures how fast a flame travels across a material once it is lit.
The same principle applies to military hybrid and electric armoured vehicles. Whatever the ignition source, slowing fire spread inside a confined space buys critical seconds for survival.
Frequently Asked Questions
They are close but not identical: both use the same horizontal burn method on a strip up to 13 mm thick exposed to a small flame. The US standard is a federal regulation with a fixed limit of 102 mm per minute. ISO 3795:1989, confirmed by ISO in 2025, is an international test method, and the acceptance limit comes from the regulation or customer specification that calls it up. Many laboratories test to both, so ask for a report that names the standard your contract cites.
The full FMVSS 302 text is available through the Electronic Code of Federal Regulations at ecfr.gov, under Title 49, Part 571, Section 571.302, which links to the official annual edition as a PDF on govinfo.gov. NHTSA also publishes its laboratory test procedure, TP-302-03 of 18 October 1991, as a PDF on nhtsa.gov. It sets the uniform test and data recording format that NHTSA’s contracted laboratories use for compliance tests.
No. FMVSS 302 applies only to materials used inside the occupant compartment. Exterior body panels, under-hood components and other external parts are not covered by this standard, and separate fire standards may apply to them where required. The S4.1 list does include wheel housing covers and engine compartment covers: what counts is whether the material lies within 13 mm of the occupant compartment air space, not what it covers.
Not by law when the vehicle is manufactured for, and sold directly to, the US Armed Forces in conformity with contractual specifications: 49 CFR 571.7(c) exempts it from every FMVSS. The standard then applies only where the contract names it. A commercial truck certified for sale in the US keeps its FMVSS compliance when a defence fleet buys it, and a civil version of a military vehicle, built for sale in the US, must comply like any other motor vehicle.