Torque through the gearbox - drive - is reduced when your foot is on the brake pedal. If you come off the brake and onto the accelerator too fast, you rush the smooth take up. Try holding the car on the handbrake and you'll feel much more of a pull. Personally, I think VAG should have included torque reduction on the handbrake, too. There's a knack to being smooth when lifting off the footbrake and applying throttle, but it soon becomes second nature.