The red and white lines on the Audi A6 seat represent the heating function of the seat. Generally speaking, this kind of chair has two lines of different colors, which are marked as red line and white line respectively. Usually the red line is the heating device connected to the seat, and the white line is the power supply and control signal connected to the control panel.
When you turn on the seat heating function, you will send an instruction through the control panel to make the red line heating device work and make the seat heat quickly. In addition, different models and styles may have different colors and marking methods. You can check the vehicle manual or consult a salesperson for more details.