xclream

Hi all: The other day, I came to a full stop at an intersection, there was this car in front of me. She started to roll and I followed her, then for an unknown reason, she stopped again and I was looking to my left to make sure there wasn't any traffic coming to T-bone me, I didn't pay attention to her and then BAM, I hit her rear bumper. Luckily, both cars were OK, there were only a few very hard to notice minor scratches.

My question is, I thought all W205 C300s were equipped with Anti-Collision System that either alarms us or brakes for us? No? It beeps once a while in traffic and I know my car brakes on its own because a few times after the traffic light turned green, I accelerated too close to the car in front, it braked on its own and scared the heck out of me.

Can anyone shed some light on this?

Sam Manuel

You have expectations of that stuff , Thats interesting ! I assume mine doesn’t work , one time it applied breaks for me and ever since I worry when it will do it again , I just want to shut it OFF ! but I’m too lazy to do it every.

only thing I rely on or value a lot is the blind spot but the rest is just a bonus if it works I’m happy but 99% I try to stay alert and drive as if it’s a 90’s Mercedes with no fancy systems.

I worry it will break and get me rear ended

xclream

I don't have expectations ..... I just want to know how/when/what the system works exactly ..... If a clear object (car) is in-front of me, and I was going about 5mph, the system didn't even detect and engage to stop the vehicle, then how would I trust this thing to work properly when I'm on the highway going 70mph?

I looked and researched everywhere on the Internet, and I cannot find any written official documents on how it functions exactly. That's why I'm asking if anyone would know.

Gungaslow

I think it only is active above 20mph.. so it won’t help in a fender bender or small rolling accident

Sam Manuel

Actually i I think it’s only passive after 20 mph cause it beeps at me all the time but it has never taken action while I’m going fast.

Sam Manuel

It’s hit or miss with me too , it beeps at me and breaks for me whenever it wants .even on the brand new E class nobody seems to know how it works , I think only Tesla has figured it out but like I mentioned when I’m going fast it seems to be only passive .

i don’t have distronic though , just the basic stuff. Idk how it behaves like on cars with that extra stuff.

xclream

Sorry but I disagree on that it only functions above 20mph.

Because on numerous occasions, from a complete stop, when the light turns green, I gas it too fast the system thinks I was about to rear-end the car in front, it beeps and brakes HARD and bring it to a complete stop for me.

Always freaks me out because I am always afraid the car behind me will rear-end me.

GerritKw

Read the manual maybe?
CPA+ starts working from 7kmh so approximately 5mph. Which sounds fully logical to me. I would not like it to keep on braking during parking.

GerritKw

That is a very good statement. The system is not there so you can drive less secure.
It's an aid to prevent colissions. Not an autonomous driving system.

GerritKw

Here a part of the manual about the brake assist:

Function

The distance warning function issues a warning at speeds:

• of approximately 30 km/h or more, if, over several seconds, the distance maintained to the vehicle travelling in front is insufficient. The distance warning lamp then lights up in the instrument cluster.
• of approximately 7 km/h or more, if you rapidly approach a vehicle in front. An intermittent warning tone will then sound, and the distance warning lamp will light up in the instrument cluster.

Brake immediately in order to increase the distance from the vehicle in front.
or

Take evasive action provided it is safe to do so.
Due to the nature of the system, particularly complicated but non-critical driving conditions may also cause the system to display a warning.
With the help of the radar sensor system, the distance warning function can detect obstacles that are in the path of your vehicle for an extended period of time.
Up to a speed of approximately 70 km/h, the distance warning function can also react to stationary obstacles, such as stopped or parked vehicles.

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:

• gives the driver more time to react to critical driving situations
• can help the driver to avoid an accident or
• reduces the effects of an accident

Vehicles without DISTRONIC PLUS: the autonomous braking function is available in the following speed ranges:

• 7 - 105 km/h for moving objects
• 7 - 50 km/h for stationary objects

Vehicles with DISTRONIC PLUS: the autonomous braking function is available in the following speed ranges:

• 7 - 200 km/h for moving objects
• 7 - 50 km/h for stationary objects

Due to the nature of the system, complicated but non-critical driving situations may also cause the autonomous braking function to intervene.

I hope this helps.