NHTSA Proposes Optional Cyan Lights to Mark Self-Driving Cars

The US National Highway Traffic Safety Administration has proposed letting automated vehicles carry cyan marker lamps that light up when the car is driving itself. The idea is simple: other road users, from pedestrians to police officers, could tell at a glance whether a human or a machine is in control. The lamps would be optional, and nothing in the proposal forces any carmaker to fit them.

What NHTSA proposed

NHTSA announced the proposal on October 23 in a press release titled "Vehicle Lighting Updates for Automated Vehicles". It is a notice of proposed rulemaking that would modernise Federal Motor Vehicle Safety Standard No. 108, the rule that governs vehicle lighting, for vehicles designed to be driven exclusively by an automated driving system. The notice was signed by NHTSA Administrator Jonathan Morrison on October 22.

The centrepiece is an optional ADS marker lamp, in cyan. The draft says NHTSA "is not proposing to mandate" the lamps, so a manufacturer could fit them or not. Where fitted, they would need to be mounted no lower than 15 inches off the ground, and the draft specifies four to eight lamps. They may switch on automatically when no occupant is monitoring the road, and must switch off automatically when a human should be. All the lamps switch together.

The proposal goes beyond colour. According to NHTSA, it also covers headlamp test voltage, the vertical arrangement of headlamps and changes to dashboard telltales. For vehicles without manual controls, a turn signal operating unit is still required, but the requirement that it cancel itself through steering wheel movement no longer applies, because there may be no steering wheel to cancel it.

How the proposal came about

Electrek, which reported the story on October 24, credits Mercedes with first putting the idea forward. The notice tells a slightly different story. It says a standard for an ADS marker lamp, SAE J3134, was first issued in May 2019, and that international bodies at the United Nations have worked on the idea. Mercedes-Benz presented recommendations to NHTSA and ran a two-year validation in California between 2023 and 2025, so it was an advocate and a tester, not the originator. The notice also cites a 2025 proposal at the UN for turquoise lighting.

Electrek also says the draft deletes the self-cancelling turn signal rule for driverless cars. The notice is narrower than that: it removes the self-cancelling feature that depends on steering movement, not the turn signal requirement itself.

China is moving in the same direction

Another government is working on the same problem. CnEVPost reported on October 20 that China's industry ministry opened a public consultation on five mandatory national standards, closing on December 19. The draft there calls for turquoise marker lights on vehicles with Level 3 or higher automated systems, on the front, rear and sides, and the lights would switch automatically with the system. The explanatory document recommends that the standard take effect on January 1, 2028. It is a consultation draft, not a final rule, and the colour differs slightly from the American cyan.

What happens next

The proposal now enters a 30-day public comment period after it is published in the Federal Register, under docket NHTSA-2026-1519 on regulations.gov. The publication date and comment deadline were not in the pre-publication text of the notice, so the exact closing date is not yet known. After comments close, NHTSA will review them and could revise the proposal before issuing a final rule. Because the lamps are optional, even a final rule would not put a cyan light on every autonomous car.

Why it matters

The question is practical. Robotaxis already operate in several American cities, and passengers, pedestrians and other drivers have no standard way to know whether a vehicle is under software control. A common colour would give regulators and the public one signal to learn instead of a different design from each company. The main open issue is whether making the lamps optional will lead to broad use, since a signal only works if people can rely on seeing it.

Does it affect India?

Not directly. The proposal covers American road vehicles, and neither source says anything about Indian regulations. It does show how regulators in the world's two largest car markets are approaching the same labelling problem, and Indian rule-makers will likely watch the outcome if driverless vehicles reach local roads.

What to watch next

Watch for the Federal Register notice that starts the comment clock, for comments from carmakers and robotaxi operators on the 15-inch height and the cyan colour, and for the final version of China's standard once its consultation ends in December.

Published October 26, 2026. Gadgets365 will update this article as more information becomes available.