Here is a look at the 2015 Audi A3 Cabriolet Body Structure and Passive Safety Features. A large contribution towards the car’s low weight is made by the hot-shaped steels that give the occupant cell its high strength. They are used in the transition to the front section, in the A pillars, center tunnel and parts of the floor. In many other areas, such as the side members, Audi utilizes high-strength and ultra-high-strength steels. At the A pillars, windshield frame, sills, B pillars bases and what is known as the heel plate of the rear seats, reinforcements compensate for the lack of a rigid metal roof.