The idea behind this system is relatively simple; what perhaps took more doing was getting the regulations in place to allow a video feed to replace the government-mandated mirror. The hardware and that rules compliance starts with what looks like a normal rearview mirror – because it defaults to being a mirror until you switch on the display or in the event the system somehow fails. Flip the little toggle at the bottom of the mirror – the one normally used to switch from day to night mode – and the reflection is replaced by a very crisp feed from a camera at the back of the vehicle. This live stream gives you a wide-angle view of what's behind, without obstruction from back-seat passengers, headrests, or any bodywork. The camera is even shielded from weather and has a coating to shed water. What you see doesn't exactly look like a normal reflection, but the quality is good enough and you see more than you would normally with something aimed through today's small rear windows.
But because it isn't actually a reflection, you have to make some adjustments. When your eyes are focused down the road, glancing at a mirror gives you a view the same distance away but in the rear. With the rear camera mirror, a glance back requires your eyes to first refocus on the display, which takes a moment. And unlike a normal mirror, which you look through at an angle, this display is angled toward the driver but projecting an image that looks straight back – no matter how you move it, the image doesn't change like a mirror's would. And because it's an image and not a reflection, you can't choose what's in focus and lose your sense of depth perception. It's not clear whether objects in mirror are closer or farther than they appear.
And there are other limitations. For instance, while the display balances bright lights and dark surroundings well at night, it is tricked by LED headlights, which flicker at a rate faster than the camera shoots. The result is a distracting strobe effect like you get when you point a smartphone camera at any LED light source. For those with migraine sensitivity, this kind of fast flashing can cause real problems. But if that bothers you at night, you can always flick the display off and use the mirror as, well, a mirror.
The Rear Camera Mirror is currently available on the XT5 crossover and CT6 sedan. The only way to get it on an XT5 is to choose the $63,890 top-of-the-line Platinum model, where it comes standard. On the CT6, Rear Camera Mirror is available as part of the $2,025 Enhanced Vision and Comfort package on the Luxury model, which brings the minimum buy-in to $61,715; the feature is standard on upper CT6 trim levels. That's a decent amount of money, but we expect the price to come down once (or if) the idea catches on and it expands to other models within Cadillac and GM as a whole.
Cadillac's Rear Camera Mirror is up against Audi's advanced Adaptive Cruise Control and the Jaguar Activity Key in our technology feature category for 2017. The winners in both the feature and car categories will be announced later this week.