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
