When when you NEED to turn it OFF?

 

umm..when you want to get off the line faster?

 

I turn it off after 700 km since I bought my car buz the milage is sucks...It works and I push it until the slippy car sign pops up on my dash board. Hold the DSC off for 5 secs at least.

Still breaking in my car now!

 

When you go autocrossing or drag racing?

Maybe if it's really nice and sunny out and want to have some fun in the twisties?

 

When you get stuck in snow and you don't want the electronics to kick in and limit wheel spin.

 

There are lots of threads about this: some always turn it off, some turn it off only at the track, and some leave it on only during inclement weather. If my car was equipped with DSC, I'd leave it off unless I was driving in the snow or rain. However, I've driven a variety of FWD, AWD, and RWD vehicles in crappy conditions for many years.

What you should do depends on your skill and experience. In any care, be careful out there and don't push your car unless you know its (and your) limits (and conditions are safe, obviously).