NHTSA proposes optional cyan marker lamps for driverless cars in FMVSS 108 notice published 26 October

The United States now has a draft rule for what a driverless car should look like from the outside. NHTSA's notice of proposed rulemaking amending Federal Motor Vehicle Safety Standard No. 108, the standard covering lamps, reflective devices and associated equipment, was published in the Federal Register on 26 October 2026 under docket NHTSA-2026-1519 and RIN 2127-AM70. Comments close on 25 November 2026.

The headline item is an automated driving system marker lamp. It would be cyan, the blue-green defined in SAE J578, with the lamp specification drawn from SAE J3134 as revised in December 2025. Crucially it is an "if equipped" requirement. NHTSA says it lacks the information to conclude the lamps are needed on every automated vehicle, so fitting one stays voluntary while the specification becomes fixed.

What the notice actually does

The proposed lamp is steady burning. Flashing is not permitted, and the lamp cannot be optically combined with other lights. Four to eight lamps would be allowed, one or two each at the front, the rear and each side, mounted no lower than 15 inches, which is about 38 cm, off the ground. Photometric limits are capped at 125 candela at the front, with 90 candela at the side and rear with headlamps off and 18 candela with headlamps on. The lamp may only be lit while the vehicle is operating without the expectation that an occupant is monitoring the road, and must go out when that expectation returns.

The second half of the notice is housekeeping that matters a great deal to anyone building a vehicle with no steering wheel. For vehicles without manually operated driving controls, NHTSA proposes to drop the self cancelling and manual control requirements for turn signal operating units, the hand or foot operated headlamp beam switching device, the ease of actuation requirement for hazard warning signals, and the turn signal and upper beam telltales. Integral beam headlamp testing would move from a fixed 12.8 volt specification to the voltage marked by the manufacturer, and the restriction on vertical headlamp arrangement would go. NHTSA expects no incremental compliance cost, since the package removes requirements rather than adding them.

Why the colour fight matters

Cyan is not an accident. California's vehicle code already carries lamp colour rules, and NHTSA says a federal specification would preempt California Vehicle Code sections 25950 and 25875 where its numbers differ from SAE J3134. A single national photometric envelope is the point. If every state picks its own shade and intensity, a validated lamp becomes impossible.

This also sits alongside the UN track. WP.29 adopted the first international regulation for fully driverless automated driving systems on 24 June 2026, together with amendments to roughly 90 existing UN regulations so they still apply to automated vehicles, with Canada, China, the European Union, Japan, the United Kingdom and the United States behind it. Lighting is being handled separately at GRE, the working party on lighting and light signalling, where an ADS marker lamp concept from GTB and a proposal to adapt UN Regulation 48 for ADS vehicles have been under review since the 90th session in 2024.

Where this leaves India

India's lamp installation requirements reach vehicles through the CMVR and AIS standards, which track UN work rather than the American FMVSS. So the cyan lamp arrives here only if GRE finishes its UN Regulation 48 text and India adopts it. That work is still open. For now the practical effect is on specification documents, because engineering and validation teams working for global customers will be asked to test lamps against 125 candela front and 18 candela rear limits long before any Indian vehicle carries one.

Sources

• Federal Register, FMVSS No. 108 proposed rule, 26 October 2026 (govinfo)
• EVXL: NHTSA proposes cyan lights for driverless cars but will not require them
• Connected Automated Driving: UNECE adopts first ever global rules allowing fully autonomous vehicles
• GlobalAutoRegs: GRE 90th session agenda and report