GLA Class (X156) Produced 2013-2020

Collision prevention assist - GLA

Old Feb 22, 2015 | 11:00 PM
  #1  
orgchem's Avatar
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GLA 250
Collision prevention assist - GLA

Trying to understand how it works. here is the link that i found.

http://next.mercedes-benz.com/en/how...-assist-works/

I have few questions hoping someone can answer them.

1) In case of crash situation, after warning sign comes on for CPA (Collision prevention assist), does the driver still need to brake or CPA automatically understands and brakes and stops the vehicle?
2) What is a pre-safe? does GLA have it?
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Old Feb 23, 2015 | 05:47 PM
  #2  
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GLA 250
I think the answers are in your owners manual assuming you received one.


1) copy and paste from my owners manual didn't format right so you'll have to check your own starting on page 66. Bottom line, yes the car has autonomous braking but I think I'll still apply the brakes myself.....


This is what's in the online owners manual:
COLLISION PREVENTION ASSIST PLUS


The innovative driving assistance system that uses radar sensor information automatically helps the driver to keep a safe distance to the vehicle in front or to stationary obstacles and assists the driver on long journeys as well as in traffic jams. COLLISION PREVENTION ASSIST PLUS gives an optical and audible warning if the driver falls below the safe distance. It extends the functionality of COLLISION PREVENTION ASSIST with an automatic braking function. This reduces the risk of front-end collisions and also serves to relieve the demands placed on the driver.


2) yes the car has pre-safe which copied nicely from the online owners manual.
PRE-SAFE®


The system uses preventative measures to provide the vehicle occupants with the best possible protection in the event of an accident. To do so, PRE-SAFE® constantly analyses the sensor data from other systems such as the ESP® Electronic Stability Program and BAS Brake Assist, allowing it to recognise severe understeering or oversteering as well as emergency braking. If a critical driving situation is detected, PRE-SAFE® can initiate various functions within fractions of a second. These include reversible belt tensioning and the automatic closing of open side windows.
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Old Feb 23, 2015 | 06:52 PM
  #3  
orgchem's Avatar
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Thanks for the information. I have checked the online manual.

Right off the bat, I will also agree that one should brake in the event of collision, with that being said.

I was looking for the information what this car can do. I wanted to cross reference what I read with what this car has. I have seen videos of crash tests with cars equipped with ABS. In most of the tests, vehicle actually stops if it detects an obstacle, if that's the case i think this would be the future. This is what I found in manual.

Autonomous braking function:

If the driver does not react to the distance warning signal in a critical situation, COLLISION PREVENTION ASSIST PLUS can assist with the autonomous braking function.

The autonomous braking function:
1) gives the driver more time to react to critical driving situations
2) can help the driver to avoid an accident or
3) reduces the effects of an accident.

It says if the driver does NOT react then it can help the driver to avoid an accident. It may or may-not, but I am interested to see the crash report of this car how it did for ABS. I have seen crash tests in youtube for this car, but they did not specifically show anything for ABS.
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Old Feb 23, 2015 | 07:21 PM
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GLA 250
Originally Posted by orgchem
Thanks for the information. I have checked the online manual.

Right off the bat, I will also agree that one should brake in the event of collision, with that being said.

I was looking for the information what this car can do. I wanted to cross reference what I read with what this car has. I have seen videos of crash tests with cars equipped with ABS. In most of the tests, vehicle actually stops if it detects an obstacle, if that's the case i think this would be the future. This is what I found in manual.

Autonomous braking function:

If the driver does not react to the distance warning signal in a critical situation, COLLISION PREVENTION ASSIST PLUS can assist with the autonomous braking function.

The autonomous braking function:
1) gives the driver more time to react to critical driving situations
2) can help the driver to avoid an accident or
3) reduces the effects of an accident.

It says if the driver does NOT react then it can help the driver to avoid an accident. It may or may-not, but I am interested to see the crash report of this car how it did for ABS. I have seen crash tests in youtube for this car, but they did not specifically show anything for ABS.
I've been trying to convince my neighbor to let me drive at his car broadside to test the system while he's sitting in his car. So far he hasn't agreed.
Mine beeps at me once a week or so as I approach cars that are turning off the road and it actually helped get my attention once in traffic. So far I don't think it's actually applied the brakes. I'm hopeful that I never need to find out if it works but that it does work if needed. Good luck with your research.
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Old Feb 24, 2015 | 12:52 AM
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Mercedes GLA
Ik weet wel als ik te Dicht op Een Voorganger puist, HIJ advocaat Een waarschuwing en Remt Automatisch af.
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Old Feb 24, 2015 | 06:39 AM
  #6  
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Originally Posted by gjan
Ik weet wel als ik te Dicht op Een Voorganger puist, HIJ advocaat Een waarschuwing en Remt Automatisch af.
Goed om te horen dat het werkt. Wees voorzichtig dat dichtbij!
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Old Feb 24, 2015 | 06:56 AM
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Mercedes GLA
Het werkt echt goed.
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Old Mar 13, 2015 | 12:27 AM
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I just picked up my GLA this week and I'm not sure if this feature is working. The manual says "the detection of obstacles can be impaired if: new vehicles or after a service on the collision prevention assist plus system. Observe the notes on the section on break-in".

In the break-in section, it says "The sensor system of some driving and driving safety systems adjusts automatically while a certain distance is being driven after the vehicle has been delivered.... system effectiveness is not reached until the end of this teach-in procedure."

Anybody know how many miles this is? I tried speeding up until I got near the back of the car in front of me and I didn't get any warnings even though the feature says on. Also, in the "assistance graphic", I was expecting to see the distance to the car in front of me, but I just have a blank road with my car showing on the display, so it seems useless. Is that normal?

Finally, any owners in Canada? I thought Distronic was standard, but my car doesn't have it. Now looking at the Canadian website, I don't even see Distronic mentioned for the GLA.

Thanks!
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Old Mar 13, 2015 | 11:07 AM
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2015 GLA250 4MATIC
My dealer said when the cars first arrived they took them to an airfield and had each of them test the CPA. They had them drive into a barrier at 15 miles per hour and not lift the foot of the pedal or try to break. It is supposed to kick in if it detects no input from the driver to correct an imminent collision after the alarm sounds.
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Old Mar 14, 2015 | 01:08 AM
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Yes - for MB the standard workshop/training/education workshop demo's CPA+ (the + represents autonomous emergency braking) - approaching a foil-covered-foam-block-barrier at 15 mph constant speed - no brake pedal - and CPA+ "alarm" kicks in about 25-30 ft from barrier - and full-ABS-brake stop egaes at about 15 ft - and at that speed full stop completes about 4-5 ft from the barrier.

If the brake is "tapped" after alert the CPa+ BRAKING will not ENGAGE - if after alarm stops - you press the brakes (versus tap) - then BAS assist will engage ABS and you will come to full stop sooner than CP alone..

Also note - MB ABS operates at about 100 "pumps" per sec, versus most other vehicles "pump" at 30 per sec.

I have generated CPA "alerts" - in some instances as opposing traffic a car "wanders" at angle toward my vehicle, another instance where a took a turn at a light, and someone from off-street access pulled in front of me..

CPA+ is NOT Distronic.... but CPA+ to me is added safety value..
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