Driving the 2019 Mercedes-AMG CLS53 is an object lesson in grand touring. From the massaging seats to the all-digital instrument panel and multimedia setup to the 429 horsepower available at the mere tap of a pedal, the luxury brand’s “four-dour coupe” is a sleek, sophisticated machine built for people who wanted an AMG GT but have responsibilities (like a family) and practical needs (like room for groceries). There’s plenty of just-because wizardry to distract you from the actual driving experience, but safety features like Mercedes’ Blind Spot Assist are there to help you stay aware of your surroundings.
The idea isn’t supposed to be that you’re distracted by Blind Spot Assist. But in multiple days behind the wheel of our $106,000-plus test car, I kept asking myself: Why were these warning lights so red?
The question out of context may merit an answer similar to the one a Mercedes-Benz spokesperson gave me.
“Worldwide, red is an accepted color for indicating hazard/imminent danger,” they wrote in an email. “In combination with the triangle as an also generally accepted form for symbolizing danger, the system is highly intuitive and widely accepted.”
Seems simple enough, right? But in more than three years of working here at Cars.com (and nearly two decades of abundant non-work-related driving), I can’t recall a single car outside the Mercedes family that features a blind spot warning whose color is red. The auto industry almost uniformly seems to have agreed upon yellow or orange.
Even Mercedes-Benz started out that way. Blind Spot Assist, introduced on the 2008 S-Class and CL sedans, wasn’t always so straightforward: Originally, a combination of red and amber triangles were used to indicate that the system was ready or working at speeds of around 20 mph or more. For the 2013 S-Class and each subsequent redesign of other models in the Mercedes lineup, only the red light remained. A revised instrument-cluster menu included a “ready” status icon, which made redundant the amber light formerly signifying the ready status. But the impetus wasn’t simply a tech revision; the automaker was also listening to consumer feedback.
“Customer questionnaires had shown that Blind Spot Assist is a very intuitive and highly accepted system,” the spokesperson wrote, “but some drivers couldn’t differentiate between amber and red.
“Yellow is an accepted color for a general warning. Therefore, when deciding on the new user interface as described above, we kept the red triangle.”
The latest iteration of the system features only two states: The red triangle is either on or off, a simpler system with a welcome side-effect of clarity for the colorblind. The speed threshold has also dropped and has remained at around 6 mph since the global introduction of the 2017 A-Class (that we’re just now getting stateside for 2019).
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The feature proved especially effective for me as I drove the CLS53 around Chicago, a city famously lit orange (for now, anyway). The red triangle in the side mirrors stood out better in a way other blind-spot warning lights haven’t, and not just for their color — Mercedes notes that the triangles shine brighter in daylight for visibility and dim at night to avoid glare. So, while the Cardinal Red Metallic paintjob may have everyone else’s eyes on your Mercedes-AMG CLS53, the standout red hue of the Blind Spot Assist lights ensures your eyes can stay on where they belong: the road.
Editor’s note: This story was updated July 10, 2019, to clarify the nature of the instrument panel.
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