NHTSA Proposes Cyan Lights for Automated Vehicles

The National Highway Traffic Safety Administration has proposed a federal lighting update that would let automated vehicles use steady-burning cyan marker lamps when their driving systems are operating without an occupant expected to monitor the road. The October 23 proposal would also modernize several headlamp and manual-control provisions in Federal Motor Vehicle Safety Standard No. 108.

This is a notice of proposed rulemaking, not a final rule. Automakers cannot assume the proposal is law, and the public comment period does not begin until the notice appears in the Federal Register. NHTSA said comments will remain open for 30 days after publication under docket NHTSA-2026-1519.

What NHTSA is proposing

The most visible change would create a standardized meaning for cyan exterior lights on vehicles equipped with an automated driving system, or ADS. Under the 66-page proposed rule, manufacturers could install front, side and rear marker lamps that illuminate when the vehicle is operating without the expectation that a human occupant is watching the roadway.

• The lamps would be optional, not required.
• The permitted color would be cyan, defined as a blue-green color under SAE J578.
• The lamps would burn steadily rather than flash.
• Front and rear installations could use one centered lamp or two symmetrically mounted lamps.
• Side installations could use one or two lamps on each side.
• All installed ADS marker lamps would switch on and off together.
• They would have to deactivate when a vehicle is operating with the expectation that an occupant is monitoring the roadway.

NHTSA is trying to prevent a patchwork of colors and patterns that could confuse drivers, pedestrians, cyclists or law-enforcement officers. The agency’s proposal says a familiar, standardized lighting scheme could help people quickly recognize that an ADS—not an attentive human driver—is controlling the vehicle.

Cyan was selected partly because it is distinct from the red, amber and white colors already assigned to common vehicle-lighting functions. NHTSA also says the proposed blue-green shade is distinguishable from the blue used by law enforcement. The proposed marker lamps would be less intense than emergency lighting.

The proposal goes beyond robotaxi marker lights

The rulemaking would revise other parts of FMVSS No. 108, the federal standard governing lamps, reflective devices and related equipment. One change would replace the fixed 12.8-volt test condition for integral-beam headlamps with the voltage marked by the manufacturer. NHTSA says modern integral-beam units, including long-life LED systems designed for a particular vehicle, no longer need the same standardized test voltage created for older lighting technologies.

Replaceable-bulb and sealed-beam headlamps would continue to be tested at 12.8 volts. The proposal therefore does not discard the existing requirement across every headlamp type.

NHTSA also wants to remove a rule requiring the lower beam to sit above the upper beam when separate headlamps are stacked vertically. Minimum and maximum mounting-height requirements would remain. The agency’s position is that modern lighting can provide adequate road illumination without prescribing which beam must be on top.

Vehicles without steering wheels get targeted exceptions

Several proposed changes address vehicles designed without manually operated driving controls such as a steering wheel or brake pedal. Current language assumes a human driver physically operates turn signals, hazard lights and headlamp beam switches.

The proposal would keep the underlying lighting functions. A driverless vehicle would still need a way to operate turn signals and switch headlamp beams, but the mechanism could be automatic rather than a hand- or foot-operated control. Existing requirements would continue to apply to vehicles that do have conventional controls, even if those vehicles also include an ADS.

That distinction matters because the proposal is not a blanket exemption from vehicle-lighting safety rules. It is a targeted attempt to remove requirements that serve no practical purpose in a vehicle that has no human driving position.

Mercedes testing helped shape the discussion

The proposal cites SAE J3134, a voluntary marker-lamp standard revised in December 2025, along with work by international regulators and manufacturers. Mercedes-Benz previously tested turquoise marker lights on five vehicles in California from 2023 through 2025 and argued that 360-degree visibility could help other road users and police recognize when an automated system is active.

Mercedes received state-level exemptions in California and Nevada in 2023 for DRIVE PILOT vehicles, but those approvals were limited and did not create a national federal standard. NHTSA’s new proposal would establish performance specifications within FMVSS No. 108 if it becomes final.

What the proposal does not do

• It does not require every automated vehicle to display cyan lights.
• It does not approve a particular robotaxi service or operating area.
• It does not certify that any ADS is safe enough for driverless deployment.
• It does not replace state rules governing where automated vehicles may operate.
• It does not create an immediate deadline for automakers.

NHTSA has not quantified the proposal’s costs or safety benefits. Because the lamps would be optional, the agency expects manufacturers that do not want them would face no added expense. NHTSA says standardization may reduce confusion, but it cannot yet estimate how many vehicles would be affected.

Why it matters for the next wave of automated vehicles

The federal proposal arrives as companies move from small demonstrations toward broader deployment plans. A separate Greater Paris driverless pilot bid targets service beginning in 2028, while General Motors has outlined plans to extend eyes-off driving to future pickups and SUVs. Those projects involve different vehicles and regulatory systems, but each raises the same basic question: how should a vehicle communicate that automation is in control?

The marker-lamp proposal addresses communication rather than driving performance. NHTSA is separately developing its first federal motor vehicle safety standard for ADS performance. The agency also says this lighting proposal is separate from a negotiated rulemaking effort announced earlier in October for other portions of FMVSS No. 108.

What happens next

NHTSA signed the proposal on October 22 and announced it on October 23. The agency will accept public comments for 30 days after publication in the Federal Register. The official record will be available through docket NHTSA-2026-1519.

After reviewing comments, NHTSA could issue a final rule, revise the proposal or withdraw it. Until that process is complete, cyan marker lights remain a proposed federal option rather than a nationwide requirement.

Featured image: Mercedes-Benz DRIVE PILOT test vehicle with turquoise automated-driving marker lights. Archive/illustrative press image from 2023; it is not a NHTSA prototype. Courtesy Mercedes-Benz via its official media release, used for editorial reporting under the Mercedes-Benz Media terms.