Go from 60 to 80 with no CC On, let the throttle go at 80 on the gear of course and see how long it takes to slow down to 60. Maybe it does it so gently that I just haven't noticed any breaking
Interesting if my doesnt brake and all other do...

Is it braking by engine or actually uses brakes? If it does use brakes I would expect brake lights to come up as well to warn the cars behind.

Thats what I mean, my brakes in this scenario dont come on, at that speed engines slows the car fairly quickly from 80 to 60

When I've done it and I've been using it a lot recently, the brake lights come on.
I can see the 3rd brake light on in my rear window cause of the tints.
You can also feel it on the brake peddle cause its a little harder than normal.

The D3 will infact apply up to 15% braking force when using the cc standard cc not acc.
If you set it to 40mph and theres a slight incline both signals from the g meter and accelerometer and level sensors will then adjust the cars speed by using both the gears with downshifts and also the brakes and you will see your rear centre brake light up at night as it dose so fully automated

This is standard on all A8 D3 with Cruise Control :)