Quote:

Is the stopping distance shorter with ABS?

No! From early commercials, it may have looked like you could stop on a dime. That instantaneous stop is not realistic. When braking on dry or wet roads your stopping distance will be about the same as with conventional brakes.

You should allow for a longer stopping distance with ABS than for conventional brakes when driving on gravel, slush, and snow. This is because the rotating tire will stay on top of this low traction road surface covering, and effectively "float" on this boundary layer.

A non ABS braked vehicle can lock its tires and create a snow plow effect in front of the tires which helps slow the vehicle. These locked tires can often find more traction below this boundary layer.

landroverer wrote:

But if you jam the brakes on and all four wheels slide, how does the car know you are still moving?

Thats the whole point of ABS (Anti Blocking System).it does.
the system applies & dis-applies the brakes very fast..to simulate cadence braking (what some of us were taught before ABS !)

The whole point is you dont have to think "how hard do I press....oh I am skidding"....& you can concentrate on steering whist the car is doing all the clever stuff stopping.
The development of what we all (or almost all) of us have & use now is a Bosch development...the original car systems were Lucas Maxaret...fitted to Jensen...I am told originally devised for airplanes (by whom I dont know but reckon it would be Lockheed)

One of my Disco 2's had its system fail....if any locals to me are reading this they will realise the place where I tested this "Churn Milk Lane" in Halifax - very steep, cobbled road also narrow with dry stone walls inches from your shiny bodywork. Every so often I would venture down this lane & test the HDC...all well & good that on a D2 you have to be in low range to get this. Fortunate for me.
SWMBO said"why inst IT making that funny noise"...err I had just thought the same no HDC & gathering speed...I just changed down to LR 2nd & did the standard Defender thing of letting the engine & 4wd system do the work...it did.
At the bottom of the hill (Shay Lane - I got a whole bunch of warning lights...no ABS, no HDC no Traction control...oh me somethings wrong
but... "4 wheels on my wagon I still rolled along"...unbelievebly strange feeling..OK I had brakes provided by the D2 back up / fail safe systems (there are five levels of this).
My D2 was still under warranty & the whole ABS module (which does ABS & HDC & Traction) was swapped out....lots of questions from LR HQ this was a very rare occurence...how did I cope ?....what did I do ?...what had I done ?

ABS is good.very good but it isnt infallible..you have to keep your wits about you & keep a good distance from the thing in front of you..ABS cant apply retro rockets....LR vehicles have gears which you can also use if you have to. Engine braking is available & you should know how & when to apply it.
LR Experience (Coniston Hall) used to do a test witha D2 in a field with wet grass to show you the difference between a vehicle with & without ABS...this is where I learnt to use it & respect the fact it may be taken away when you need it most...

landroverer wrote:

But if you jam the brakes on and all four wheels slide, how does the car know you are still moving?

It knows everything 8) Well nearly everything ....there are a whole raft of sensors to tell the vehicle what's happening....but what it doesn't have sensors for is the back end of something if you have been too late in applying the brakes ...or the sharpness of the corner you are heading into at 50 instead of 25 ....the be all and end all is that these systems will do their best to rectify your balls up ...but it's not infallible