@AppleFan1Thanks for the kind words. Your question is an excellent one because it gets to the heart of the ownership experience with a car this advanced. It's about the gap between the simple description in a manual and the complex, nuanced reality of how these systems operate day-to-day.

Let's dissect this, because what you're experiencing is not a failure—it's the car operating as designed, and understanding the "why" is key.

These vehicles are not just transportation; they are a sanctuary, filled with what I call "intelligent overkill." These are features that work quietly in the background to make the experience safer, more convenient, and more seamless. The biometric system is a perfect example.

The intermittent login failure almost always comes down to a handful of environmental and physical blockers:

• Extreme Lighting: The camera in the driver's display can be washed out by direct sunlight or struggle with the harsh shadows of a very dark garage.
  
• Facial Obstructions: Polarized sunglasses are a known issue that can interfere with the system's infrared sensors.
  
• Steering Wheel Position: This is a subtle one that I've noticed personally. If the Easy Entry/Exit feature leaves the steering wheel in a high position, it can sometimes physically block the camera's line of sight to your face when you first get in.
  

However, the real "insider" detail that explains the inconsistent timing is what I call The Authentication Window. The system isn't constantly scanning. When you open the driver's door, it activates an authentication cycle that lasts for only about 10-15 seconds. If you're occupied during that brief window (looking at your phone, adjusting things), the system times out for security reasons and defaults to the fingerprint reader.

Decoding the Prompts: The Camera's Three Different Jobs

This is where it gets interesting and where most of the confusion lies. That single camera in the driver's display serves multiple functions, and they don't all behave the same way—a nuance that has evolved since the 2022 models.

1. For Facial Recognition Login: If an authentication attempt fails or times out, the system will silently default to the fingerprint reader. It does not prompt you to move. It prioritizes a seamless (if failed) login attempt over bothering you.
   
2. For ATTENTION ASSIST: This is the car's driver drowsiness monitor. If the camera's view is blocked for an extended period, it can't perform its critical safety function. On newer models (primarily MY24+), the car will proactively display a message like: "ATTENTION ASSIST cannot function. Please adjust seat and steering wheel position." This is an intelligent safety override.
   
3. For AR-HUD Calibration: This is the source of that familiar "6 dots" prompt some of us have seen. During the initial setup of a driver profile, the system must calibrate the Augmented Reality Head-Up Display to your precise eye level. It uses the camera to track your eyes as you adjust your seating position to align with the on-screen target. This is a one-time setup prompt for that specific feature.
   

It's also important to note that the cameras in the overhead console are for the MBUX Interior Assistant. This system enables several "intelligent overkill" features. It allows for gesture controls, such as pointing toward the rearview mirror to activate a reading light or sliding a hand under the console to open the sunshade. Critically, it also monitors the driver's head and eye movement; if you glance at the passenger-side mirror and then reach for the controls on the door, the system intelligently pre-selects that mirror for adjustment, eliminating a step. On vehicles with the Executive Rear Seat Package, a separate camera system provides similar gesture controls for rear passengers.

Ultimately, the fingerprint request isn't a sign of a flawed system. It's a sign of a secure one, with a built-in, reliable fallback. When facial recognition works, it's not just about logging in; it's about the car seamlessly adjusting your seat, steering wheel, and side mirrors to your exact presets before you even think about it. The fingerprint is the safeguard for that automated convenience. It's one of the many layers of thoughtful engineering that, once understood, elevates the ownership experience from simple A-to-B conveyance to an appreciation for the machine itself.

 

Thank you for the detailed reply. Since I posted that I had trouble with facial recognition, I called Mercedes. The next day I received an email for a fix. Basically, I had to start my profile from scratch. This time I had at least six steps that came up. One of the steps asked to check off fingerprint sensor (I didn’t bother to activate this option), facial recognition, and voice assistant. I activated these two only. Bingo! I finished the setup. Now the facial recognition works 100% of the time. I love it. I may have skipped a step here (perhaps something that was called biometrics) in the user profile.

 

Facial recognition worked for me 100% of the time from day one except when I'm working a mask. I can have a few stubs of hair on my face with no issue, too.

 

Here is another little question. This new 2025 EQS 580 no longer adjusts to the speed signs. However, if I exceed the speed limit, the recommended speed flashes and also there’s a brief alarm to remind me that I’m going faster than the speed limit.

Is this the way it’s suppose to work on the current EQS?

 

That's a classic settings configuration issue, not a system malfunction.

The fact that the car sees the signs and warns you means the Traffic Sign Assist camera is working perfectly. The system is simply set to "notify" rather than "act."

Here's the fix:

1. Go to Settings > Assistance > Driving.
   
2. Look for the setting called "Active Speed Limit Assist" or "Route-based Speed Adaptation."
   
3. Change it from "Show Only" to "On."
   

The reason Mercedes makes this a selectable option comes down to a fundamental difference in driver philosophy. Some owners prefer to be informed of the speed limit but want to retain 100% manual control over their speed at all times. Others prefer the convenience of the car adapting automatically as part of the semi-autonomous driving experience.

Your car is simply set to the more manual of those two modes. Toggling that setting will give you the automatic speed adjustment you're looking for.

 

The 2025 EQS 580 has a little different options. These options are “Speed Limit Warning” and visual or visual and audible. You need to click one or the other. There’s no other choice. I didn’t have the speed limit warning clicked on in the past. I hope that automatically changes the speed to correspond to the signs. I will test it later today.

 

@AppleFan1

Thanks for the follow-up. I went out to my own 2024 EQS and I see exactly what you're describing. You're in the right area, but the wrong sub-section, which is an easy mistake to make.

Based on your description, you are in this menu path:
Settings > Assistance > Traffic Sign Assist
That section is only for the warnings—the visual or audible alerts. It will never change the speed of the car.

To get the car to automatically adopt the speed limit, you need to be in the Driving sub-menu. Here are the explicit directions based on the video I took:

1. Start on the same Assistance screen.
   
2. On the menu on the left, tap on the word "Driving".
   
3. A new list will appear on the right. In that list, find and tap on "Speed Adjustment".
   
4. A pop-up window will appear. In that window, you must turn ON the toggles for both:
   • Maximum Permissible Speeds
     
   • Route-Based
     

Enabling those two toggles is what gives your cruise control (DISTRONIC) permission to use the camera's speed sign data to actively control the car's speed.

I made a quick video that walks through these exact steps to make it crystal clear:

Hope this helps you find the right spot! Let me know if that works.

**** Turn down the volume, I adjusted the size but forgot to change the volume. ****

 

Thank you very much. It looks like it will be tomorrow before I can test it. It should work now.

 

Your instructions were spotless. My car now automatically adjusts to speed limits.

 

Excellent. Glad to hear that sorted it out.

Happy to help. Enjoy the feature!

 

Wow - I have always wondered why the car can't auto adjust - this was gold. I just enabled it - and can't wait to try it out. Thank you.

 

Oddly for me, that was the first thing I turned off. I drive in HOV, and 45 mph at some section will just PO other drivers off.

 

That's the classic tactical question these systems present: how to balance automated compliance with real-world traffic flow.

My own protocol is straightforward: I let Distronic lock onto the legal limit, then immediately override it by +5 mph.

My calculus on this is simple: another driver's impatience is a non-transferable liability. They don't pay the fine, they don't take the points, and they certainly don't absorb the insurance hike for the next three years.

Therefore, their opinion is given the exact weight it deserves.

 

Glad to hear you found it helpful! Please let us know if it worked for you.

 

Oh - I did not think this through. I do exactly the same - I always drive +5 - +9 of speed limit. If I enable both, I assume the moment I bump it up, it will go back down?

 

@nevermindme
That's the perfect follow-up question, because you've hit on the exact real-world trade-off of this feature.

To answer you directly: No, it will not constantly fight you and go back down.

The car's logic treats the automatic speed adjustment as a one-time event each time it passes a new speed limit sign. It will adjust to the new limit, but the moment you manually override it by bumping the speed back up to your preferred +5 mph, your input takes precedence. The car will then hold your new speed until it detects the next speed limit change, at which point the process repeats.

And this is where the system's logic can become a real-world annoyance. From my personal experience, that constant cycle of the car adjusting down and me having to immediately bump it back up can become a tedious ritual, especially on local roads with frequent speed zone changes.

For me, I've found it's actually less tedious to leave the system on all the time and deal with the manual overrides than it is to constantly dive into the MBUX menus to toggle the feature on and off.

However, for those who desire more granular control, adopting a two-pronged protocol is a perfectly valid approach:

1. City & Suburban Driving: Turn Active Speed Limit Assist OFF to maintain full manual control.
   
2. Highway & Interstate Driving: Turn it ON to act as an invaluable and almost invisible safety net.

 

Thank you! I drove out to test today. Here is what I observed, with both options enabled:
a) If you are driving on a road with 40mph as a limit, but you manually override to 45, the car will not fight you and will not go down to 40, as, you said
b) If you cross new speed signs that showcase the same speed limit as it earlier saw, it will not reduce the speed. That means, if I manually set it to 45, and it crosses 3 more 40s - It won't reduce the speed. This is excellent
c) The moment it finds a different speed limit (higher or lower than the current one), it will adjust (I think that is what you meant when you said different speed limit sign, now that I think about it)
d) It ignores signs that warn you of an upcoming speed limit (good)
e) It ignores school speed limits in yellow even if the lights are flashing (not great, but I'll live with it)
f) It ignores yellow speed signs in general (typically ramps/conditionals)

b) was critical for me - and it behaves as expected. I have a road leading to my house that is generally 3-4 signs of 40 and then there is a warning sign that its 30 ahead, a drop down a small hill and you have 30, with a speed camera. I sometimes miss slowing down - and this setting worked perfectly. It maintained 45 (manual) for the road, did not slow down at the 'warning 30 up ahead' sign but slowed down as soon as I got close to the 30.

Appreciate your insights!