I did this test on my D3:

To test:

Driving along, put the car in tiptronic and use the shifter to put the car in the highest gear it will go, 4th or 5th is ideal if you are doing > 30mph.

Now, floor the car and only if the kickdown is working will it change gear. If it is not working, then because you have tiptronic selected it will not change gear. Only the kickdown function (and anti-stalling) can override the gear selection in tiptronic.

Where's the switch at ??

Behind the throttle.
Looks like a bump stop.

Ah ok will have a look
Thanks Andy

Sadly as I expected, mine was on!

So is mine

Amazing, my was disabled, but driving very often in Sport I would't notice the difference, when I put the foot down I do get the faster gear :D
My gearbox just knows me very well :D

It's good to have it anyway especially if you are in D.

Good tip guys +++

I think we need to bump this one.

Didn’t even know my car ( 2006 a8L 4.2tdi ) had a kickdown switch until yesterday. Thanks to this forum.

Checked the switch and low and behold it was off. I could never understand why the Car seemed to “do little” when floored and when already up to speed.

I have a stage 2 map on mine, knew it was rapid from low gear and slow speeds, but never seemed to have the same performance when you needed a kickdown.

Switch on now and holy sht, it is like a torpedo now. No need to go into smode on the gearbox now just plant it!

Best mode ever

Hold on... wait... I am positive I've read in a technical document that the s8 does not have a physical kickdown switch. It has a "feedback" thing that makes it feel like a switch but it does everything by position sensor...

What do you mean it was disabled?

Pre-facelift, cable throttle, no kickdown switch.
Post-facelift, fly-by-wire throttle, physical kickdown switch (lockable button) on the floor under the pedal.

I always preferred the pre-facelift throttle response in every way.

Edit: Just to clarify, that difference is for a D2 as that is what the question appears to relate to. This is a D3 thread and all D3's are FBW.