syswei

If the car senses an imminent crash, will Distronic Plus automatically brake the car if I don't even have the system turned on? I never use cruise control, but would consider the Distronic Plus package for safety reasons, if it acts as a safety device even when cruise control is not engaged.

trumpet1

Regardless. Get the distronic!!!! You'll use cruise control again because I didn't use it either for 20 years until now due to increased traffic. The distronic makes driving so much more pleasurable.

To answer your question: No. It will not brake the car if it is not turned on. Even when it is turned on, you only will get 40% braking when approaching a vehicle or object. It is not intended to substitute driver awareness but it really aids in decreasing driving fatique and aggravation during cruising conditions.

However, their is a setting , which when turned on, that keeps the radar active even when you are not using distronic cruise control. This setting will sound a beeping alarm whenever you are approaching a vehicle or object at a very high relative speed. It will alarm you to slow down quickly or an imminent crash could occur. Very nice feature indeed. In fact, I can remember one time that if I didn't have this feature, I would have plowed into a car sitting still on a busy thoroughfare (with no turn signal and brakes working) She came to a complete stop with no warning at all. It happened at a place you would have never suspected !!!

LETO

Agree with trumpet1 100% I have distronic plus and his last paragraph is an accurate description of the advanatage of the safety net it throws.

Also park assist is awesome when parallel paraking, especially if you are paranoid about curb rash. Parak assist coupled with back up camera makes parallel parking very easy.

Blindspot assist is also very useful as the side mirrors on the S are small. However, if they were bigger they would ruin the lines of the car. Blindspot assist helps maintain the asthetics of the car while solving the problem the design presents.

For the price, and features you get distronic is a no brainer!

WSH

DistPlus (and incld BlindSpotAssist) is an outstanding active safety feature worth every penny....

I never drive w/cruise ctrl activated....enjoy modulating throttle and brake, even in traffic; and IMO changing driving speed/style/lane position vs inept nearby/following drivers is a critical defensive driving tactic, even in stop-and-go driving; in my expce, low-value cars are often driven by weaker drivers who tailgate/have weak brakes/are distracted, etc and increase odds of one being rear-ended....and SF Peninsula has some of fastest urban fwys in world, so cruise ctrl is fairly irrelevant...

BSA is also really useful for those who aren't thorough re: looking to sides and in all mirrors before changing lanes....really useful in urban driving where bikers often weave through lanes of stopped/slow traffic....

But, even w/o cruise activated (Trumpet1, could they have changed feature from '07 to '08, as my CL's DistPlus safety features seem to work w/o cruise ctrl active?), always have benefits of audible warning if approaching car/object at dangerous closing speed....and will activate BrakeAssist, w/40% braking if driver doesn't respond....

Diesel Benz

I thought Trumpet1 had a later model but mine does "only" give an audible warning in the above scenario, the does not brake (have not tried but this is my understanding). From 2008 model year onwards (if I remember right, current models at least) this was improved, the car should still give a warning tone first but soon after that if the driver still does not brake, the car takes over. Obviously we agree on the enhanced behaviour.

One of the Distronic Plus improvements that I would consider reasonable as a SW update to the car.

trumpet1

WSH and Diesel:

You guys may be right (or actually we both may be right). I know that I have the option of turning on and off my radar which functions when I am not in distronic mode. When on, it alerts me when I am approaching a car too fast. Each time this happens, I've never sensed any braking from the car.

However, I also have the option of turning on and off what is called "pre-safe braking". I don't think it means that it will brake the car for me, but instead, makes braking more quick and efficient whenever I am in a hard braking panic situation. I think it boosts the brake action 40% to compensate for me applying the brakes milliseconds too late in an impending crash situation. But it only does that if , and only if, I press the brakes myself.

That being said, the 2008 models may behave differently. I simply do not know and I may be wrong about my own car but this is how I understand it.

NJS430

Pre-Safe braking will in fact brake if you do not. See description below -

If the distance to the vehicle in front is too short, the distance warning lamp lights up in the instrument cluster. You will also hear an intermittent warning tone if you are rapidly approaching the vehicle in front.
If you yourself do not brake or steer, the vehicle will automatically brake slightly. In cases of increased risk of a collision, PRE-SAFEŽ is activated

The radar sensors are also used to control the level of brake boost based on the distance between you and the object with which the system senses you are going to collide with. I think many people don't understand that distronic-plus is much more than just cruise control. You don't want to order one of these cars without it.

trumpet1

What year model are you referring to? Page 58 of my 2007 manual discusses Pre-Safe, and it never mentions that. What page did you get that from?

When I googled it, this is what I found which seems to suggests that you are very much correct.

Since my car has PRE-SAFE braking option, I would assume my car does have the automatic braking you've suggested.
The above is something I found while reading up on the S-Guard edition S class (bulletproof model).

NJS430

Try looking at page 76 ..... What month/year is your manual.

trumpet1

Thanks but my page 76 speaks of anti-theft alarm systems. My manual was dated April 06, 2006. My car was built in 10/06 and I bought it 11/06/2006. Apparently it didn't take long to get here from Germany. Less than maybe 2 weeks total.

syswei

Thanks, guys, I'm considering a 2008 so this is helpful. I wonder just what is meant by "slightly"? Does a 70mph crash become 50mph? Why couldn't they just take this all the way and brake down to the speed of whatever the driver was about to hit?

NJS430

Look for the heading - PRE-SAFEŽ Brake* (vehicles with DISTRONIC Plus* only) Should be in the Saftey and Security section under Driving Saftey Systems. I believe everybody with Distronic-plus has this feature. I don't know how long you have to wait before it kicks-in. So far I have only heard the warning beep on mine. Not sure I have the nerve to test it.

trumpet1

LOL I was just thinking the same thing 10 minutes ago. I want to test it but I'm afraid I will screw up and not hit the brakes soon enough. One thing is for sure, I hope I never need these features in real life.

Has anyone followed your car while someone else is driving it to see how often the brake lights come on while the distronic slows down the car??? I often wonder how many times the taillights are coming on without my knowing it. I know it doesn't always use the brakes but I wonder what the threshold of deceleration is before the brakes are applied and lights come on?
Also, I was reading where the brakes lights will flash quickly upon heavy braking. I wish I could see that in action.

I also read where that if you slam on the brakes while going over 40 mph and come to a complete stop, the emergency flasher lights come on automatically and the brake lights stay fully lit up until you once again proceed at a speed of over 6 mph. Neato

NJS430

My sense would be that they still give you the option to hit something intentionally. The system will do what you suggest so long as you have your foot on the brake. But if you never press on the pedal, then the system would not know if you were trying to hit something to avoid something else?

NJS430

When I first started using Distronic-plus I was afraid of getting rear ended. I have since learned that it does a better job and brakes less erratically then I do. I can see the brake light come on in my rear-view mirror at night.

The beauty of the system is that it constantly measures and responds to the speed of the vehicle in front of you. It doesn't respond to brake lights - only speed. Unfortunately - you do. That is why you'll have a desire to cancel the system when you see the brake lights of the car in front of you come on and the distronic-plus system just keeps the car going at full speed. I've learned the system actually will do a better job then me 98% of the time.

Still can't believe I almost didn't order it. Distronic-plus should not be an option.

trumpet1

Here.Here!!
I don't use it when traffic is so thick that their is a tendency for other drivers to cut in front of you while you are trailing someone in the left lane. Once it is that thick and fast, I feel it is time to be my own driver. However, when I'm in thinned out city traffic or especially on long trips, I can go for 150+ miles and never touch a pedal.
Something else that is interesting in the history of the distronic system that I didn't know is that it actually was placed in the latter models of the W140 before it made it into the W220.

check this out:

http://www.whnet.com/4x4/distronic.html

syswei

Well, the driver is still fully in control of the steering. If the car may hit one object or another or both, then imho the system should slow the car automatically to the speed of the slowest of the two objects.

In a litigious society like the US, MBUSA is opening itself up to legal liablity, imho. It is one thing not to build the system into every car...that can be claimed to be a cost issue. But to build it in and allow it to brake automatically but only "slightly" is imho unwise. If I were in a Distronic-equipped car without cruise engaged, and god forbid hit and killed someone, yes it would absolutely be my fault; but in my mind MB would also be at fault, for building in the capability to brake automatically, but not brake automatically to a stop.

On the other hand MB does go farther than Lexus, for instance, which doesn't brake automatically at all with their system.

WSH

Always difficult to design these systems for the myriad of scenarios one deals w/in real-world....

Part of why I refuse to use cruise ctrl is that I would argue that much of active safety in many scenarios depends upon continual driver awareness and risk/reward judgments of many elements (incl likely behavior of fellow drivers) in surroundings if need to make instantaneous decisions in an emergent situation.....need to quickly calc and bet on pavement/weather vs traction/braking dists/stability of one's car in an evasive maneuver; likely behavior of cars one is following; cars in nearby parallel lanes if need to do sudden evasive maneuver; closeness of the car following one...is it a rusty SUV w/an inept driver that will rear-end an AMG w/high-powered brakes in any sudden deceleration?...or is it a guy in an '08 S65 following w/ample distance and who seems focused on driving/traffic??

Would argue this emergent, complex fwy dynamic is more common in SF/LA regions (having been in regions like NYC/Chicago for yrs, it takes some time to become accustomed to much higher fwy speeds often seen on CA urban fwys).....where various high-speed fwys have flow speeds of 80MPH+, yet traffic can be dense w/many inept drivers sometimes creating chain-reaction mayhem; in any emergent braking, the car/SUV following is likely a 10yo POS w/far inferior brakes and an inept driver....so the competent MB driver needs to have a plan to avoid being rear-ended and avoid any collision.....and needs a car that will best protect one if the unavoidable occurs....

Have never been in a collision (but have had enough near-misses through no fault of own to appreciate importance of superb active safety and, more importantly, smart judgment on part of driver, not just a backup computer system)....and suspect the guy driving the $100K++ car will be sued in any collision, no matter fault (guys driving 10yo, <<$20K-value cars/SUVs tend to have little to lose and much to gain via a contingency-based personal injury lawyer shakedown)....so tend to risk-profile and drive carefully vs other cars and have ample liability coverage w/a reputed insurer....

trumpet1

Great points. Also don't forget to look for people who are intexicated (texting on the phone).

AsianML

Nice term. LOL

Have any of you ever driven in the Greater Toronto Area during rush hour? It's 90 MILES per hour and UP in rush hour. It's even scarier when traffic dies down a bit if it ever does.

kevine310

I don't recall where I heard it from, but I believe distronic will automatically apply some braking pressure a few seconds (I think it's 2) before impact to reduce the severity.

don't quote me though.

Diesel Benz

I guess I have to repeat the same comment I made earlier on this thread: early W221 cars do not have the automatic braking feature (when distronic is not on), just the warning tone. Later models have the warning tone first, soon followed by the car braking (if the driver still does not react).

I believe this was intended from day one but they had to make some changes after the car crashed at a press event...

One should not count on this braking feature, the car would not necessarily have enough time to stop, but it would always help to reduce damage.

PRE-SAFEŽ Brake (vehicles with Distronic Plus*)

• warning you of an imminent collision
• reducing the vehicle's speed by automatically braking lightly
• triggering preventative passenger protection measures (PRE-SAFEŽ)

Risk of accident PRE-SAFEŽ Brake is only an aid to assist you when driving. You are responsible for maintaining a safe distance from other vehicles, the vehicle's speed and for braking in good time. Always pay attention to the traffic conditions. You may otherwise recognise dangers too late, cause an accident and injure yourself and others.

The PRE-SAFE Brake uses the radar sensors to detect obstacles which are in the path of your vehicle for a long period of time. If you approach an obstacle and PRE-SAFEŽ Brake detects a risk of a collision, the system will initially alert you both visually and acoustically.
Risk of accident Only clearly identified obstacles will trigger a warning and initiate braking assistance by PRE-SAFEŽ Brake.
In particular, the detection of obstacles can be restricted if there is:

• dirt on the sensors or if the sensors are covered
• snow or heavy rain
• interference by other radar sources
• strong radar reflections, for example in multi-storey garages

PRE-SAFEŽ Brake does not react to persons, animals, oncoming vehicles and crossing traffic.
PRE-SAFEŽ Brake may not detect narrow vehicles such as motorcycles and vehicles driving on a different line to your vehicle.

If the distance to the vehicle in front is too short, the distance warning lamp lights up in the instrument cluster. You will also hear an intermittent warning tone if you are rapidly approaching the vehicle in front.
If you yourself do not brake or steer, the vehicle will automatically brake slightly. In cases of increased risk of a collision, PRE-SAFEŽ is activated

cat797

2012 will heavy brake its self to 8 miles an hr.with cruise on s550 4matic