PSM

[Licker and Poker]

Hi your opinion please
Just trying to buy my first Boxter S and wonderd should PSM be high on my list of priorities or is it not that important
Thanks in advance

 

[oliver]

It's nice to have and very clever, but a competent driver shouldn't need it.

 

[Carl.Young]

[FONT=Verdana"]I don't have it, was never an option I looked for specifically. I don't miss it, however one thing I'd point out in relation is your choice of wheels - if you go for an 'upgraded' set (mine are 18" with 265 rears) you may well find that the fatter rubber can make the back end a wee bit edgy in greasy conditions, especially when they're part worn. I've had a couple of 'interesting' moments - mostly pulling away from standing as the S has a lot of power low down - but a little bit of restraint goes a long way. I'd say it's down to your preferences and your confidence.

 

[davel]

There's so much bollox posted about PSM from the hairy chested brigade as they presume you can replace it with skill.

It has 14 sensors that constantly (100 time per second) monitor the car's movement through the world looking for any deviation between what you would like to do and what the car is actually doing. It can brake individual wheels to effect instant and efffective steering, alter speed and even change gear to try and make the car go wherever you're pointing the wheel. No driver in the world can do this with the same speed and effectiveness as PSM.

Regardless of your driving skill the road can be icy, there could be a big crash ahead, whatever, it's a driver aid for those otherwise impossible (for humans) situations.

You may never need it, but when you do it will probably save your life. And your passengers.

The reality is that if you have PSM you are 40% less likely to die in a car accident.

 

[Mark Elder]

Where does that 40% statistic come from? - Interested to see how it does the comparison.

 

[jw2015]

I agree entirely with DaveL. I put PSM at the top of the list when looking for my Boxster and it has come in useful on at least one occasion, where the rear kicked very unexpectedly in an easy corner at relatively low speed, due to oil or something similar on the road. I'd like to think I corrected the car but I think it was the PSM, because at the time I was not even concentrating, as I was just trundling along gently enjoying the view.
It is true that a skilled driver may not need it but how many of us get to practice our power-sliding skills to the extent that we're happy to deal with any situation. I've been on the track in awful conditions, specifically to see what the limits of the car are, and with PSM on I was able to throw the car into any corner without worrying about my lack of skill. Just to prove to myself that it was the car and not me that was dealing with the conditions, I switched the PSM off for a lap and spun the car in the hairpin on the first attempt. I came away confident that if I really misjudge things, it'll probably save my @rse, especially in awful conditions. It does work very well.
You can also argue that if most of us will run out of bottle before the Boxster loses grip, and that's probably the case until you hit a greasy patch unexpectedly, in which case you'll be glad of a PSM safety net. If you do become hairy-chested and you think you're skilled enough you can always switch it off.

 

[Guest]

I drove a 911 C4S yesterday and really got to appreciate benefits of PSM. Slamming on the anchors at 100mph and the car being completely stable was unbelievable.

 

[oliver]

ORIGINAL: jw

I have been on the track in awful conditions, specifically to see what the limits of the car are, and with PSM on I was able to throw the car into any corner with worrying about my lack of skill. Just to prove to myself that it was the car and not me that was dealing with the conditions, I switched the PSM off for a lap and spun the car in the hairpin on the first attempt. I came away confident that if I really misjudge things, it'll probably save my @rse, especially in awful conditions.

I think that highlights my reservations about PSM - drivers who rely on the car's electronics to get them out of trouble when their skill or judgement runs out, in the same way that some owners think that a 4wd car is somehow safer than a 2wd car.

The original Audi TT was a case in point. By Audi's standards it had quite pleasant handling. But many owners expected it to be foolproof, with a few high profile accidents. These were nearly all judged to be driver error, but Audi decided to recall and modify the aerodynamics and suspension on all TTs, and fitted ESP. The result was less engaging, more sterile handling but a greater margin of safety against driver error.

Safety should begin and end with the driver. I'm sure that many drivers of earlier Porsches are more adept at 'roadcraft' because they make greater allowances for the unexpected through keeping their distance, better anticipation, keeping the car balanced through smooth control of the brakes, throttle and gear changing, driving the correct line, always looking out for the unexpected, etc.

Yes, if we accept that overall driving standards are poor, then ESP type systems probably do contribute to wider safety on our roads, but it would be far better if people learnt to drive properly in the first place, invested in regular tuition and drove within the limits of their abilities and prevailing conditions.

Jeremy Clarkson once said that the seatbelt and airbag did not make better drivers or reduce accidents - but a sharp bayonet, sticking out of the steering wheel, one inch from the driver's heart probably would [:-].

 

[sawood12]

ESP or PSM wont make anyone a better dirver but they will get people out of trouble if they either overcook things and suddently find themselves in an unexpected situation. No matter how competent driver you are unexpected things will happen (that patch of diesel on the apex of the roundabout or blind corner for example) and in the very brief milliseconds you have to take action in a moment of panic you WILL loose it - and if you manage to get out of the situation unscathed don't fool yourself that it was through anything but sheer luck. Don't listen to anyone who tells you not to get the electronic aids. For a road car you should get all the electronic safety and stability aids you can afford. There are no gravel traps on any A or B road i've ever driven on. Being brave or stupid on the track is an entirely different situation to being brave or stupid on the road.

Having said that you are a fool if you purposly drive your car to the extent that the electronic aids are saving your backside. They are and should be treated as a safety net.

 

[davel]

I have PSM and it's never intervened except when I've triggered it playing around with it in safe circumstances.

It's a safety device just like ABS and traction control and air bags and crumple zones and role cages, etc. You'll probably never need it except in extreme circumstances when everything goes to shit on you. If you don't want safety you're an idiot and a danger to everyone else on the road.

The 40% figure comes from Bosch who invented it. If you have PSM, try an experiment. Drive into an empty roundabout and gently accelerate. Keep the lock on and keep accelerating (gently and smoothly). Stay legal, be aware of others entering the roundabout and if you crash don't blame me, I'm not driving your car.

Once you've done this you'll understand that no human could possibly do the same in the same car without PSM.

Edited to add: DO NOT TRY THE ROUNDBOUT EXPERIMENT UNLESS YOU HAVE PSM - TRACTION CONTROL AND/OR DRIVER SKILL WILL HAVE YOU EXITING THE ROUNDABOUT BACKWARDS INTO THE SCENERY.

 

[Black80XSA]

PSM comes into its own if you hit diesel spillage or something similar where no driver can react as quickly.

However it can't deny the laws of physics - if you drive like a prat then it won;t save you - remember the grip levels of the Boxster are high, if you lose it then you're in for a big impact

 

[davel]

If you hit diesel you lose grip and PSM can do nothing. PSM doesn't alter grip at all. PSM activates when the car stops going in the direction you're steering. PSM tries to make the car go in the direction you're steering.

Oversteer & understeer are both occasions when the car isn't going where the wheel is pointing. PSM will kick in and brake individual wheels to sort this out (this may not be what you want but for the ordinary driver it can be a life saver). If you're at the cars limit (on a track) it won't kill the understeer and let you go faster, it'll kill the power until the understeer goes away. On the 986 it triggers when it detects 7 degrees of slip. You can turn it of but it will turn itself on again if it detects 'panic braking'.

Much more useful is when there is an incident ahead (a car pulling out of a side road, an accident, a kid running into the road). In a PSM car you should just drive round the problem and let the PSM help you with the 'extreme maneuver'. In these circumstances performing the maneuver without PSM would be impossible, regardless of driver skill because of the way it applys breaking to each wheel individually to make the car follow the way you are steering. You simply cannot steer that quickly in a 'stable' way by altering the direction of the front wheels alone. This is why it's called Stabilty Management. It keeps the car stable in during extreme maneuvers.

 

[Black80XSA]

ORIGINAL: davel

If you hit diesel you lose grip and PSM can do nothing. PSM doesn't alter grip at all. PSM activates when the car stops going in the direction you're steering. PSM tries to make the car go in the direction you're steering.

Oversteer & understeer are both occasions when the car isn't going where the wheel is pointing. PSM will kick in and brake individual wheels to sort this out (this may not be what you want but for the ordinary driver it can be a life saver). If you're at the cars limit (on a track) it won't kill the understeer and let you go faster, it'll kill the power until the understeer goes away. On the 986 it triggers when it detects 7 degrees of slip. You can turn it of but it will turn itself on again if it detects 'panic braking'.

Much more useful is when there is an incident ahead (a car pulling out of a side road, an accident, a kid running into the road). In a PSM car you should just drive round the problem and let the PSM help you with the 'extreme maneuver'. In these circumstances performing the maneuver without PSM would be impossible, regardless of driver skill because of the way it applys breaking to each wheel individually to make the car follow the way you are steering. You simply cannot steer that quickly in a 'stable' way by altering the direction of the front wheels alone. This is why it's called Stabilty Management. It keeps the car stable in during extreme maneuvers.

talk to 'scouser' about what happens when a 996 hits a large pool of diesel dumped in the road by a local farmer - several near spins, lots of flashing lights and a safe stop on the tarmac, missing all hedgerows and trees. there was so much diesel around the police insisted they cleaned the underside of his car at their depot before allowing him to continue on his journey !!

 

[channella]

I don't think you can buy a new Boxster today that isn't PSM equipped.

As to "driver skill"; PSM does allow some oversteer and understeer, but it cannot address a lack of driver judegement rather than skill regarding what is appropriate on the public road.

Knock yourself out on the track however...

 

[Richard_Hamilton]

There's an interesting article here: [][]

http://www.porscheclubgbforum.com/tm.asp?m=231422

 

[marcusLondon]

Ooohhh, I love a good catfight! The fact is that everyone has valid points to make and that if PSM was an option on a car of an age you are looking at it would be well worth considering finding one that has it as: i) it's unlikely to attract a huge margin over one that doesn't and ii) in certain circumstances of misjudgement it will undoubtedly save your bacon as it can react and correct for instabilty in a way that a human cannot. Have any of you got individual brake pedals for each wheel? Thought not. It's that simple.

The fact that many [most, almost certainly - though I don't have statistics!] of the times when it steps in will be down to "driver error" is irrelevant. It helps. And anyone who drives more quickly than their skill, judgement and the conditions allow is asking for trouble - because no matter how clever the computer it is not infallible and cannot overcome the laws of physics. But if it's there, buy it - then forget you ever did......

The diesel spill point is interesting - once traction is broken things are inevitably going to get interesting. I'm sure it's down to the amount of diesel spilled and levels of traction and many other factors (so, if things are not hopeless give me PSM every time!) - but here's something interesting. I drove my 987 S on some ice in a huge supermarket carpark near me last winter. Guess what? The PSM was worthless and the car would do little but spin the rear wheels, then sometimes not bother allowing me any throttle at all, and sometimes allow me to oversteer wildly. At least when I turned it off I was able to induce power oversteer when I wanted it, to actually allow me to corner rather than understeer being the only option! And as to the ABS! With sport mode turned off the brakes simply didn't work! When I turned S on, at least they were "influenced" by what I did with the brake pedal!

My final though regarding the roundabout test: Whilst driving on a (moderate) steady lock and gradually increasing the power is certainly a test of the PSM, it is more or less guaranteed to generate understeer in a road set-up car. This is unlikely to be the ideal example of bacon-saving but will demonstrate what is going on - but what person continues to add to underteer whilst heading for the outide of the corner? A far more likely scenario is going into a corner too fast on a mid or trailing throttle (or indeed accelerating and getting understeer) and then either braking mid corner or easing off. Whilst this latter is a great way to tighten up a race-car mid turn, it is not recommended without a lot of run-off and I for one am not about to try either in my road car.... So I go back to my earlier thoughts:

If you have it, forget it's there then thank it when you do something dumb. If you buy a car where it was an option, try and get it and then ditto. If you don't have it, hope you never have cause to regret you didn't. The worst feeling in the world must be... "I wonder if...."
Marcus