MB_MA

Hi Members,

I recently took delivery of a new 2021 GLC300 4Matic SUV and was happy to see that the Rear Cross-Traffic Alert now comes standard. What a great feature to prevent collisions from cars coming at right angles when backing out of tight spots.

My question to the forum is: does it actually work in your real life experience? I ask because when I went to test it in a parking lot, it seemed underwhelming in the “alert” department. Maybe I’m not seeing all the potential here, or maybe I received a bum unit on my new car, but here’s what I did and the results:
- my partner is in reverse in a parking spot waiting to back the car out
- I quickly approach the rear bumper a foot or so behind at a 90 degree angle to the car, mimicking an approaching vehicle
-partner begins to back out as a collision (with my body) becomes imminent (note that no one was run over by this experiment . )
​​​​​​- see what happens…

My expectations were that the car would throw an audible alert. I wasn’t sure if the system was “active” or not, so I thought the car might actively brake as well. Sadly, in every case in this test, I would have been run down an an approaching object. There was no audible alert, and no active braking. What did happen is that a small (I mean SMALL) red triangle would appear in the front screen of the touchscreen multimedia display when I was a foot or so from the rear bumper. No sound. No active assist. And only a foot away. This is what really confused me since a person naturally will be turning their head to the rear, looking for cross traffic and pedestrians approaching. How are you supposed to be alerted if you’re looking for cross-traffic in the opposite direction of the alert notification? An audible alert would be so helpful here, and even better with an active assist.

Has anyone else had experience with this now standard feature? I’m not sure if I have a bad system, or just a poorly designed experiment, but if any forum members out there have real experience and thoughts on it, I would be happy to hear to them! Thank you from a MB newbie!

MBguy013

MB implementation of the cross traffic alert is terrible and I'm really disappointed with it. It is nowhere close to what the sensitivity was in previous non-MB vehicles I've owned and that is in both our GLC and GLE.

wkc987

It did work once for me, and one time a false alarming on my 2020 GLC.

The most recent one is from yesterday while I am backing up from a parking lot. My view is blocked off from the truck beside. Even the rear view camera was not able to catch the view. When I was in reverse and letting the vehicle roll a little bit, the car beeping me and I felt the brake is automatically applied a little bit (not fully but can fell the car slows down). And indeed there was a car drove by. However, the parking lot is those 45 degrees one that usually on the street. (not 90 degree)

Another time was a false alarm when I was backing up to park into a parking slot. There were no vehicles or person and I was not sure what kind of invisible things it detected. The car applied the brake all the way down and stop. I was like "What the heck just happened🤣🤣" (The brake is applied all the way down until I shift it to D again)

Sometimes when I was waiting for a traffic light, some pedestrians walked so close to my front bumper. In that case the car reacts with a audible warning and triangle in the dash. I am not sure, maybe the system treat different objects differently🤔🤔

dalazernet

The rear cross-traffic alert is just that… looks at traffic coming while slowly backing out of spaces. It doesn’t recognize people/pedestrians etc.

Direct from Mercedes:
Rear Cross-Traffic Alert is not a substitute for actively checking around the vehicle for any obstacles or people. It may not detect certain objects based on their size, path, proximity or speed and angle of approach, or due to sensor obstruction, and does not control steering angle. See Operator's Manual for additional information, tips and warnings

I’ve never had mine detect people walking, but it does frequently notify me of cars driving past as I’m backing out of spots.

superswiss

I can't specifically comment on the GLC, but it does work for what it's designed. The problem is your test. It's mainly detecting moving objects crossing behind you, not somebody standing there. For stationary objects, that's what the parking sensors are for. I do get an acoustic alert in my C63 besides the red warning triangle. It's not the loudest alert, but once you learn what it is, you know what's going on. It also activates the brakes if you don't slow down or stop yourself. I actually find the implementation very good. In some other brands such as Audi, it's super sensitive and slams on the brakes for nothing. I had an Audi loaner once that slammed on the brakes while I was parallel parking, because another car passed me on the road, but I wasn't even close to backing into it. I would have first hit the car behind before I would have hit the passing car. So far I've not had false positives with the Mercedes implementation and it never slammed on the brakes as long as I let off the throttle when it detected passing traffic.

mercedes77429

I agree that the Cross Traffic Alert doesn't work well. I haven't received alerts; rather the car just brakes hard--with no warning--if it detects a vehicle while backing up. My previous Lexus did a much better job of alerting for vehicles.

abacnus

It does alarm constantly for me on 2020 GLC, but just too much. It scares me much more than the rear traffic as it makes a HARD and DEEP break.