Brian Latouf, Director
Global Vehicle Safety
General Motors LLC
30001 Mound Road
Warren, MI 48090
Dear Mr. Latouf:
Thank you for your letter informing us about the new Full Display Mirror system that your company plans to install inside a passenger car model, the 2016 MY Cadillac CT6. I want to thank you especially for the initiative your company took in engaging with this agencys staff regarding your mirror system. The National Highway Traffic Safety Administration (NHTSA) seeks to facilitate innovative safety technologies. This type of exchange between your company and NHTSA about new technologies is an example of how we can work toward improving vehicle safety.
Although your letter did not expressly request our views about the status of your mirror system under the Federal Motor Vehicle Safety Standards (FMVSSs), subsequent discussions with your company indicate that it does, in fact, desire our views. Based on the information in your letter and on our observation of the system during a demonstration has your company conducted near our headquarters, our understanding is that the Full Display Mirror system has two modes:
(1) In one mode, it acts as a conventional mirror and shows a reflected image of the rear of the vehicle interior and of objects behind the vehicle at unit magnification; and
(2) In the other mode, which the driver can activate, it provides an unobstructed, video-generated image provided by a camera located at the rear of the vehicle.
When the driver activates the second mode and looks at the mirror system, he or she sees the video-generated image, instead of the reflected image, in that location. The field of view angle (measured from the focal point of the camera) in the video-generated image is considerably larger than that in the reflected image (measured from the projected eye point).
S5.1-S5.1.2 of FMVSS No. 111, Rear Visibility, require each passenger car to have an inside rearview mirror of unit magnification meeting certain field of view and mounting requirements:
S5.1 Inside rearview mirror. Each passenger car shall have an inside rearview mirror of unit magnification.
S5.1.1 Field of view. Except as provided in S5.3, the mirror shall provide a field of view with an included horizontal angle measured from the projected eye point of at least 20 degrees, and a sufficient vertical angle to provide a view of a level road surface extending to the horizon beginning at a point not greater than 61 m to the rear of the vehicle when the vehicle is occupied by the driver and four passengers or the designated occupant capacity, if less, based on an average occupant weight of 68 kg.
S5.1.2 Mounting. The mirror mounting shall provide a stable support for the mirror, and shall provide for mirror adjustment by tilting in both the horizontal and vertical directions. If the mirror is in the head impact area, the mounting shall deflect, collapse or break away without leaving sharp edges when the reflective surface of the mirror is subjected to a force of 400 N in any forward direction that is not more than 45 from the forward longitudinal direction.
However, as you point out in your letter, the inside rearview mirror of a passenger car need not meet any field of view requirements in S5.1.1 if the car also has a passenger side outside rearview mirror meeting the requirements in paragraph S5.3 regarding magnification, stability, absence of sharp points and edges and adjustability. We assume that you pointed this out because the 2016 MY Cadillac CT6 will have such a passenger side outside rearview mirror.
S5.3 provides in full:
S5.3 Outside rearview mirrorpassenger's side. Each passenger car whose inside rearview mirror does not meet the field of view requirements of S5.1.1 shall have an outside mirror of unit magnification or a convex mirror installed on the passenger's side. The mirror mounting shall provide a stable support and be free of sharp points or edges that could contribute to pedestrian injury. The mirror need not be adjustable from the driver's seat but shall be capable of adjustment by tilting in both horizontal and vertical directions.
While your Full Display Mirror system incorporates a variety of innovations, we believe that the narrow question you have effectively raised in your letter is whether the Full Display Mirror system can be regarded as an inside rearview mirror of unit magnification within the meaning of S5.1. We have carefully considered that narrow question and provide the following opinion, which is limited to the applicability of Standard No. 111 to your mirror system and to the unique facts set forth in your letter.
While the Full Display Mirror is an item of motor vehicle equipment that performs additional driver activated functions, we do not believe that the fact that it performs such functions alters its basic identity as an item that includes an inside rearview mirror of unit magnification. Given that an inside rearview mirror of unit magnification is not (in the case of the CT6) required to meet any field of view requirements in S5.1.1 (although it might meet them), and given our assumption that the interior mirror meets the mounting requirements in S5.1.2, we believe that your Full Display Mirror system includes an inside rearview mirror of unit magnification within the meaning of paragraph S5.1 and that it meets the only applicable requirements of paragraph S5.1. This conclusion holds regardless of which mode or test condition your Full Display Mirror is in, i.e., in the Full Display Mirror on condition or in the Full Display Mirror off condition. 
Separately, given that the apparent sharpness of the video image provided by the video mode of your Full Display Mirror system, as observed during the NHTSA demonstration, we do not currently have safety concerns about your system. We note, however, if a manufacturer were to offer a system whose design, performance or usage was found to create an unreasonable risk to safety, that system would be subject to a recall.
We thank you for taking the time to consult with NHTSA regarding this new technology. As we stated above, NHTSA encourages technological innovations that have the potential to provide additional safety benefits to the American public. We look forward to working further with you and other automotive industry stakeholders on such matters.
If you have any questions concerning this letter, please contact me.
Paul A. Hemmersbaugh
Ref: Standard No. 111
 As stated above, we assume that your vehicle will have an passenger side outside rearview mirror meeting the requirements of S5.3 (and therefore is not subject to any field of view requirements in S5.1). We further assume that your Full Display Mirror system meets the mounting requirements in S5.1.
 Fundamentally, the Full Display Mirror is an item of motor vehicle equipment that has a reflective surface showing an image of objects towards the rear of the vehicle at unit magnification.
 See, for example, our October 2, 1990 letter to Mazda (Kadoya) regarding test conditions. See also the discussion in our October 7, 1994 proposal on manual air bag cutoff devices (59 FR 51158, 51160) of multiple test conditions in the section of the preamble entitled III. Legality of Air Bag Cutoff Devices.