I noticed that in the on-dash menu there is a pre-safe option and when you click to activate it there is a little diagram in the corner of the dash.
Just wanted to get an idea of what this means, why it's there, how many people have it on etc.

 

pre safe will move the pass. seat and rear seat if equip with elect rear seats into a safe position if the car thinks it is about to get into an accident also will close the sun roof if opened,does not move drivers seat

 

True, it also does other things like raises the rear seat headrests even if there was nobody at the back (just tried it when someone was coming from a parking lot at a bit high speed...).

But this menu on the cluster would not switch on and off these safety features. The menu should be for the warning sound for objects in the front where collision appears possible. Early cars only give a warning tone, later ones should give a tone first and would apply brakes on their own later on if the driver does not react. This can be switched on/off (actually separate menu settings for the warning and braking).

Activating/deactivating the distance warning system*

This function is only available with Distronic*. Use the buttons on the multi-function steering wheel.
Press or to select the Assistance menu.
Press or to select Distance warning system.
Press .
If you want to change the setting, press again.

Activating/deactivating the PRE-SAFE® Brake*

This function is only available with Distronic Plus*. Use the buttons on the multi-function steering wheel.
Press or to select the Assistance menu.
Press or to select PRE-SAFE Brake.
Press .
If you want to change the setting, press again.

 

my driver's seat moved into a more favorable impact position this past winter when i was coming in too hot to a red light and slammed on the brakes. the car operated flawlessly by effectively cutting me out and having the computers take over. not only did the pre-safe activate by moving my head rest up and the seat back to a position almost 90 degrees perpendicular to the seat cushion but also stopped the car (on a lot of ice and snow!) prior to impending impact.

THIS is why i buy these cars and drop $100,000: for the brilliant saftey design and engineering in these automobiles!

(tbenz - not trying to start an argument or flame your response/ i am not that way at all ,,, but i say what i say here in case YOUR car's driver's seat is not fx properly. have it checked out. it should move. after all, what would be the purpose of having a pre-safe system if it doesn't protect the driver?)

 

I can't say that I have experienced pre safe in action but all that I 've learned about it, the driver seat is not going to move the only change in the driver seat that takes place is the contour seat blatters will fill, they don't move the seat because they don`t want to move it when the driver is trying to keep control of the car. I could be wrong but all the MB info states the seat doesn't move.

 

so the pre-safe is activated when you have the little diagram in the bottom or it is DEactivated with the little diagram in the bottom?
It seems a little illogical to have a diagram to show it is activated, but that's what mine is doing.

 

The seat does move. According to Mercedes:

On emergency braking the front seat belts in the S-Class are pre-emptively tautened and air chambers in the dynamic multicontour seats (available as an option) are inflated, supporting the driver, front passenger and rear passengers and holding them more securely in their seats. In addition the front passenger seat is moved into the optimum position with regard to fore-and-aft lo-cation and the angle of the seat cushion and backrest, ensuring that the belt and airbag are able to operate to best effect. In the rear of the S-Class PRE-SAFE® corrects the backrest angle and seat cushion setting. The rear head re-straints are also raised.


If there is a risk of skidding, the system also begins to close the S-Class’s side windows and the sliding sunroof. This means, for example, that in the event of a side impact or a rollover the windowbags are better supported. This PRE-SAFE® measure also reduces the risk of occupants being flung out of the open side windows or sliding roof or of objects penetrating the interior.

 

Two different discussions of which this one is off topic but from above I read that the drivers seat does not move, unless you consider the air chambers inflating. It says the passenger seat and the rear seats are moved, there from you should interpret that the front seat position is not changed.

 

Can you please clarify what is your interpretation about pre-safe? I'm repeating my previous post and the quote from the user manual, pre-safe features are always on, mostly. The only options that can be switched on and off are the distance warning tone and automatic pre-safe braking. Seat adjustments and seat-belt pre-tightening etc. work irrespectively of the IC menu settings.

If your question was about the little icon at the IC, the features are on when the icon is shown, not the opposite.

 

okay that was my question -- so the distance warning tone and pre-safe braking only turn on when you have the icon in the corner. Thanks diesel!

 

My read of above is driver's seat doesn't move...

Suspect most drivers fail to program their seats (esp seatback angle)/head restraints/bolsters/steering wheel for maximal driving ergonomics/safety....

In fact, from my reading of how active head restraints function, it's not clear to me that AHR are safety-additive for those who have pre-programmed their head restraints properly....

To anyone who programs proper ergonomics of car and drives w/roof and windows closed (moronic to drive w/them open if one wants to optimize safety risks), I suspect PreSafe's greatest value is advanced warning of DistPlus of imminent collision and coupling to BrakeAssistPlus....and/or ESP's smart/fast reactions to dynamic instability...and pre-tensing of seat belts....

 

You are correct in your read. However, from the one experience I had during a panic braking event, it sure felt like the driver's seat was moving.

 

I wouldn't doubt you...many materials from MB/AMG are erroneous/incomplete....most marketers (who write/edit these materials) are clueless re: basics of engineering and safety....and I suspect many engineers in Germany (like most competent engineers) tend to have a dim view of marketers, so "communication" issues exist....

For ex., I believe mbusa web site (among other official MB sources) indicated CL63/65 has front active head restraints....I emailed AMG US to verify; off-hand they did not know correct answer....after several days (and presumably finding someone in MB/AMG safety engineering to clarify) they responded that none of CL's have AHRs....not compatible w/seat struc design....

 

well - as i said in my post above - my seat moved along with the tightening of the seat belt irrespective of the literature. so - maybe MY car is not working as designed - but if it's not - that's ok with me because as i experienced, the car detected a potential impact and readied me (the driver) for it. so -- i'm not taking the car in to the dealer to have it checked; i appreciated the safety movements in the driver's seat.

i hope NONE of you find yourself in a situation where you have to "test" the system. safe travels, all. cheers.

 

ajm and MBZ, do you guys recall to which position PreSafe moved the driver's seat? Presuming that's optimal position vs impending crash, would program seats/head restraints/bolster positions to match that "idealized" position, to save precious secs preparing in any poss collision situation....

Would suspect MB/AMG safety engineers have endless disputes w/the marketers who insist upon idiotic stuff, like sunroofs, Pano roofs, cupholders, etc etc, that helps sell cars to safety-clueless, sloppy drivers, but compromises overall active/passive safety....

After much reading and dynamic expces w/new S/CLs, I find it difficult to comfortably drive or be a passenger in any car, except a new S/CL....makes travel very unpleasant...as, at best, one can only get a beat-up S-Class w/o ABC or DistPlus, but w/an inept driver (who's often looking at his email while driving) in places like Manhattan/London...it's great to put one's life/health in the hands of moron limo drivers....they don't hand those jobs out to just anyone....

 

when the car detected a panic stop by me, the computers cut me out of the picture and took over. you could feel the braking action on the brake pedal. i got some warning lights too. cannot recall which ones now.

my head rest moved all the way up. it didn't have far to travel, though, as i have it fairly high to begin with.

the seat *felt* like it went 90 degrees; meaning, the backrest of the seat was perpendicular to the seat cushion. i don't know what it actually did.

the steering wheel did not move. either because it is designed not to do so (i suspect this is the case, so the drvier can continue to have control) or it was already in the ultimate crash position (unlikely).

the seat belts tightened. a lot. almost overly-constricting.

once i came to a stop (without a collision!) and calmed my heart now beating like a rabbit, i had to reset the seats and all by hitting the #1 button on the door panel. that is to say, the car did not right it self back to the original pre-emptive state.

hope that helps.

 

ajm, appreciate the summary

Indeed, have yet to trigger full-scale Pre-Safe....so always curious how safety nets function in real-world....

Suspect many drivers of new S/CL are fairly risk-oriented, competent drivers who leave ample margin for error in their driving choices, but I definitely feel much safer knowing that a thoughtfully engineered network of safety structures/technologies exists to protect one if unavoidable occurs....

Have always risk-adjusted alleged perf/luxury/daily-useability, etc of any car for its likely overall safety....and would argue new $100K+ S/CLs are worth every penny (and then some) b/c of their superior levels of active/passive safety (interestingly, most other $100K+ cars have notably inferior, more primitive safety engineering)......

 

amen, brother!

 

Seat belts tensioned with incredible force.
Drivers seatback came forward similar to AJM's description
Brake actuation was taken over by an invisible 800lb gorilla who was now stepping on the brake pedal.
Sunroof closed.

It was almost as if I suddenly became a passenger in my own car, with the Mercedes safety intervention now in control of the panic stop. I hope you never need it, but it's reassuring to know it's there.

 

So, what causes the Pre-Safe to be "unavailable"?

 

i have w221 with distronic plus i select the assistance menu but not see PRE-SAFE Brake ?!

 

Pre-Safe unavailable generally means something is wrong with the forward looking radar sensor.
When I have been in very heavy rain storms I have gotten that message - then it goes away after the rain slacks off.

I had my Pre-Safe engage on the highway one day.
I was coming up on some traffic which suddenly began coming to a halt.
I was braking somewhat strongly when someone cut over into my lane in front of me because they had nowhere to go in their lane.
The car took over by applying maximum braking force, tightly cinching my seat belt, closing the sunroof, and squawking with enough beeps and buzzers to wake the dead.
Pretty cool to see it all in action doing what it should (yes, I'm an engineer) and quite reassuring.