there is a switch

2WD mode
4WD mode
4WD lock mode.

at 2wd .. only the front 2 wheels move .. open differential
at 4wd .. all 4 wheels move .. open differential still
at 4wd lock .. it locks at 50% (if i remember correctly)

yup .. running at 2wd mode easily save 20% more fuel, but bear in mind the 4wd mechanical are on the car itself which weights additional 100kg . So no matter how you drive with the 2wd mode u wont get it as fuel save as the 2wd version

trust me, u don;t need 4wd in any of those conditions

my 6 yr old 4wd triton i think i use less than 6 hours total in 4wd mode for whole 6 yrs 

the 4wd function is juz a marketing gimmick in malaysia . i agree with lucifah .. u dont need it..
but some ppl wanted the 4wd because of the OTHER accessories..

i am from Sabah .. and i know ..
the truck 4wd is nothing to hooo haaa .. it is totally different from what an EVO X or a subaru system.. it just meant to give u slightly more traction.
IMO the ASC + 2wd is way to go already. the ASC is seriously important.. erm.. does the CKD version 2wd comes with ASC ?

Can you at least do your duly homework before commenting on things you don't even understand in the first place?

Actually dtna7 is right. Having 4WD only serves to divide the torque and power to more driving wheels. With less power/torque at each wheel they become more manageable and all that power spreads across a greater surface for better traction.

It can't be called traction control because by definition traction control is controlling the amount of power and torque a drive wheel has, by braking or throttle feathering. Going from 2WD to 4WD is nothing like traction control. But, because it does make the car far more tractable it gives a bit like the effect of traction control, but not doing anything that a traction control does.

But, dtna7 can at least be a bit less on the offence (for a lack of a better word).    But hey, no hard feelings between you two, ay?

On a side note, for normal city driving it's better to be in 2WD. The engine will experience less frictional losses and frees it up from having to drive all 4 wheels. Therefore you save more fuel. Doesn't matter if the car is heavy with load, if you have enough traction stick with 2WD. If you're starting on a slope, the 4WD may help because in 2WD the ASX as I understand it is essentially a FWD, but if you already have momentum going to a slope even 2WD is fine (you hardly see any FWD vehicle spin their wheels after a run up to a slope do you?).

In heavy rain or driving on anything that you think will offer you less traction, use 4WD. Simple.

To all ASX owner, i need you all to share me some lights. I'd got my car for the past few weeks. One thing i noticed that the sound proof of the car isn't that perfect. Despite the engine roaring (I mean if you hit the paddle harshly), when raining or vehicle pass by, I could hear it significantly. I suspect the rubber seal onto all the doors aren't good enough. Another thing is, anyone ASX owner experience the vibration sound coming from the gear knob cover? It's kinda annoying when moving on bumpy road. Lastly, some minor yet noticeable sound coming from the rear, it's like something knocking inside the trunk! I have checked everything inside, the spare tyre, tools and everything, but still couldn't find a clue. After the first service (1k), i'd mention those and they have it inspected. Somehow the noise reduced, but it still able barely hear it. Gosh, am i a perfectionist or what??

Anyone did advance sound proof to their beloved ASX?