NHTSA Seeking Input to Allow Digital Displays to Replace Traditional Glass Mirrors on Vehicles

author: Eric Walz   

Cadillac's digital rear-view mirror was first offered on the 2016 CTS, although not available in the U.S.

With all of the high-tech features being packed into modern vehicles, including the ability to navigate autonomously, one relic from a 100 years ago remains, reflective glass mirrors.

The National Highway Traffic Safety Administration (NHTSA) is seeking input for "digital mirrors" which is a new technology that replaces glass mirrors with a digital display connected to a camera mounted inside or outside the vehicle.

On Wednesday, the National Highway Traffic Safety Administration said in a notice that is is seeking public and industry input on whether to allow so-called camera monitoring systems to replace rear and side-view mirrors mandated by longstanding U.S. auto safety standards.

The National Highway Traffic Safety Administration (NHTSA) currently doesn't allow digital displays, citing safety concerns over not being able to see if the camera or display fails, as well as decreased visibility from the lower resolution of some digital displays.

Current rules require that motor all of a vehicle's mirrors be able to "physically reflect light."

However, automakers argue that the "digital mirrors" provide a much better field of view that traditional mirrors and now it looks as though the NHTSA is warming up to the technology, following their approval outside of the U.S.

The digital mirrors are approved in Europe and Japan. Last year, Toyota's luxury division Lexus said that the digital cameras enhance driver's visibility and therefore overall safety. Toyota's new digital mirrors first debuted in the 2019 Lexus ES sedan, but the option is not available for U.S. customers. 

The incorporation of digital cameras can also be used to improve aerodynamics and fuel economy, since they are less bulky than glass mirror housings that contain additional hardware for power mirrors. In addition, using smaller digital mirrors reduces wind noise leading to a quieter cabin experience for passengers.

Federal guidelines for automakers are fairly strict. Rules regulate everything from the size and color of the turn signal indicators on the dashboard to the style of the fuel pump icon. Even a vehicle's identification number (VIN), must appear in sans serif typeface.

Electric automaker Tesla and the Alliance of Automobile Manufacturers  petitioned the agency back in 2014 to allow cameras to be used in lieu of traditional mirrors, citing improved fuel economy through reduced aerodynamic drag as the primary benefit. 

Cameras feeding one or more displays inside the car could also improve rear and side visibility, including being able to see 360 degrees around a vehicle, the Auto Alliance has said.

General Motors also sought permission from U.S. regulators to use the digital display mirrors. GM first revealed the digital mirrors on the Cadillac CT6 in 2016.

But NHTSA, which has been studying the technology for the past decade, says camera monitoring systems may also introduce new safety risks. Among the concerns is the findings of  a five-year agency study of the technology on heavy-duty vehicles found the display screens were often too bright, making it harder for drivers to see specific objects on the road.

Steady improvements in cameras and vision technology however are eliminating these types of visibility concerns.

Digital "mirrors" can be combined with GPS and object detection for added safety.

In 2017, the NHTSA began testing a prototype camera monitoring system and found it was "generally usable" in most situations, and produced better-quality images than mirrors at dusk and dawn. However, the agency also found potential flaws, including displays that were too bright at night, distorted images and camera lenses that might become obscured by raindrops.

NHTSA said in a notice in the online Federal Register is seeking outside research and data about the potential safety impacts of replacing mirrors with cameras to inform a possible proposal to alter the mirror requirement in the future.

The comment period will be active for 60 days after the notice is formally published in the Federal Register on Thursday. The agency didn't offer a timeline for a final decision, but its likely that it will take years due to the bureaucracy of the federal government.

In May 2018, the NHTSA mandated the use of back-up cameras in all new vehicles sold in the U.S., but side-facing mirrors are still not required, even though the back-up camera system does not use reflective mirrors.

In the meantime, the current crop of self-driving vehicles being tested on public roads are required to have glass mirrors, although eventually there will be no human on-board to look at them.

Eric Walz

Originally hailing from New Jersey, Eric is a automotive & technology reporter covering the high-tech industry here in Silicon Valley. He has over 15 years of automotive experience and a bachelors degree in computer science. These skills, combined with technical writing and news reporting, allows him to fully understand and identify new and innovative technologies in the auto industry and beyond. He has worked at Uber on self-driving cars and as a technical writer, helping people to understand and work with technology.