NHTSA has proposed rewriting the lighting rules for cars that drive themselves

The National Highway Traffic Safety Administration wants to change how a car must be lit when no one is driving it. Announced October 23, 2026, the proposal would amend Federal Motor Vehicle Safety Standard No. 108, the federal lighting rule, for vehicles designed to be operated only by an automated driving system. It would also let those vehicles carry a standardized cyan lamp that tells police and other road users the car is driving itself.

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It is a proposal, not a final rule. Comments are open for 30 days after Federal Register publication, which was scheduled for October 26, 2026.

Standard 108 without a steering wheel

Standard 108 assumes a person sits behind a steering wheel, and NHTSA’s announcement of the vehicle lighting updates says the changes address regulatory burdens for vehicles without traditional manual controls. Administrator Jonathan Morrison said the agency’s safety standards need to keep pace with innovation, and described the package as setting clear rules of the road for automated vehicles. The release places the action inside NHTSA’s broader AV Framework, alongside other standards modernization, exemption streamlining and updated federal guidance.

In practice the proposal pulls driver-specific wording out of the standard. Per the agency’s proposal notice, requirements for turn signal self-canceling, manual cancellation and hand or foot beam switching would apply only to vehicles that have manual controls. Those vehicles would still need a turn signal operating unit and a beam switching device, and the hazard warning definition would drop the word driver. Telltale requirements for turn signals and upper beams would likewise cover only vehicles with manual controls, and the standard would use the word telltale in place of indicator throughout.

Headlamp tests and the rule about which beam sits on top

Two of the changes have nothing to do with steering wheels. Integral beam headlamps are now tested at a fixed 12.8 volts, a figure that predates LED lighting. Under the proposal they would be tested at the voltage the manufacturer marks on the lamp, so a design that runs at a different voltage can be certified as designed. Replaceable-bulb and sealed-beam headlamps would keep the 12.8-volt test.

The other change removes the requirement that the lower beam sit above the upper beam, a vertical-order rule that constrains how designers can arrange advanced lighting. Minimum and maximum mounting heights stay as they are. Neither change is limited to driverless cars in spirit, but both were drafted in the context of the new vehicle designs the agency expects to see.

Cyan lamps: optional, four to eight, and a California conflict

The most visible piece is the ADS marker lamp. The text submitted for publication, available as the public inspection copy of the Federal Register document, sets out the details. A vehicle that carries the lamps needs at least one visible from the front, the sides and the rear, each of those areas may hold one or two, so the total runs from four to eight. Lamps must be steady-burning, at least 15 inches off the ground, cyan as defined in SAE J578, and cannot be optically combined with any other lamp or reflector.

Intensity depends on whether the headlamps are on. The front lamp must reach at least 4 candela with headlamps on and 20 candela with them off, with a 125-candela maximum in both conditions, matching the limit for a parking lamp. Rear and side values are keyed to taillamp and amber side marker lamp values, with minimums multiplied by five when the headlamps are off.

NHTSA is not requiring the lamps. The notice says the agency lacks enough information to show a safety need, and that it expects no added cost for manufacturers because the equipment is optional. Its stated worry is the opposite problem: differing, non-standard supplemental lighting that could confuse or distract other road users or mask required lamps. The proposal departs from the industry standard SAE J3134 in several places, including photometry, which the agency calls a true conflict, and the notice says NHTSA tentatively concludes the federal rule would preempt parts of California’s ADS marker lamp law, Vehicle Code sections 25950 and 38750, to the extent of those departures.

Electrek, in its report on the cyan lights, notes that Mercedes first floated the concept alongside its Drive Pilot Level 3 system after a two-year California trial, and that China has drafted a similar optional standard that uses turquoise and would take effect in 2028.

Where comments go and what is still undecided

Docket NHTSA-2026-1519 collects the comments, with a 15-page limit on each submission and no limit on attachments. The Department of Transportation’s listing of the Federal Register document shows publication on October 26, 2026, which puts the close of comments around November 25. The exact date should be confirmed in the final notice.

Several questions are left open. NHTSA asked for comment on whether the hazard warning telltale should also be limited to vehicles with manual controls, and on its tentative preemption conclusions. It also separated this proposal from a negotiated rulemaking announced earlier in October, which it expects to take up other parts of the lighting standard. Whether the cyan lamp is adopted in this form, and whether California’s own version survives, will depend on what commenters from automakers, states and law enforcement tell the agency by late November.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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