E550Shopper

I've asked two salesmen this question, and got conflicting / unclear answers.

Basically, I'm trying to figure out if the "Presafe BRAKE" feature -- i..e., the component that will brake for you if you're about to rear-end someone, NOT the feature that closes the windows / pre-tensions seatbelts if you're about to wreck -- works when you're NOT using Distronic (i.e., adaptive cruise).

My MDX for example will try to brake you if you're about to hit someone, even if you aren't using adaptive cruise at that time.

Diesel Benz

Is it not explained in the manual? Early W221 cars with Distronic Plus did not do what you explain but after an update (well before the facelift) this feature was added. The car should first give a warning tone and soon after brake on its own (note, it may not prevent a collision in all cases, the intention is to reduce damage and injuries). The cluster also should have a menu where this feature can be activated or disabled.

I would assume the W212 with Distronic Plus would be the same but I did not read the manual myself (and my 212 does not have distronic, unfortunately).

Beausoleil

Pre-Safe Brake works whether Distronic Plus is enabled or not. 100%

At 1:53 the guy demonstrating in the following video makes it clear.

http://www.youtube.com/watch?v=SOH86WYyQCg

E550Shopper

Didn't buy the car yet, so don't have a manual.

But sounds like it does work as expected -- thanks guys!

Sweet video by the way...

ttoE550

The manual is available online at mbusa.com.

I certainly get the beeps warning me about my closing rate relative to cars ahead, even when I am not using cruise control. There are certain times the system is "fooled" -- a parked car on a curve, for instance, can fool it because you are headed straight for it for at least a moment, or a car turning from your lane when there is a "drive around" lane. I think that is why MB engineers set the car to brake at 0.6 seconds instead of, say 1.6 seconds, because the car can't tell if the driver intends to go around or is not paying attention and will go straight. EDIT: I guess that by 0.6 seconds from impact it doesn't matter.

LaicepsYdobon

Yes; Pre-Safe can be enabled/disabled independently of the DistronicPlus system. If you have Pre-Safe on and are driving around in town, not using DistronicPlus, you will get alerted when you are about to rear-end someone. Lots of nice videos on YouTube about this demonstration.

Here's the online manual for the car for your reading pleasure:

http://www4.mercedes-benz.com/manual-cars/ba/cars/w212/en/experience/index.html

Zinny

Does the E550 have the pre safe even if you did not order the distronic package?

LaicepsYdobon

Yes; I believe PreSafe is standard on all E-Class cars.

Zinny

Thank you.

Beausoleil

Don't confuse Pre-safe, which is standard, with Pre-safe Brake, which is not. Pre-safe Brake relies on Distronic Plus being fitted as it uses the same radar. In the UK at least, the Distronic Plus cost option includes Pre-safe Brake. I can't say whether the same is true for other markets. If they are separate, Distronic Plus must be specified before Pre-safe brake can be ordered.

To be clear, Pre-safe is the system that primes the seatbelts, closes (almost) any open windows and the sunroof and puts the front passenger seat (if electric memory seats are fitted) into the optimal position for slow developing crashes (eg slides and rolls). Pre-safe brake is something altogether more special as can be seen from the video, so it really was helpful of MB to use such a similar name.

mg-E550

I personally have had pre safe brake go off while not using distronic at the time. Was on FDR drive in NYC and was lightly braking (admittedly I was driving to close) when the guy in front of me jumped on his brakes....system literally responded before I could.