“Around 2,800 simulations and countless hours in the wind tunnel.”
“From the very start of the project, we placed a high value on efficiency and range and pursued very ambitious goals, regarding the A6 e-tron. To be honest, in the beginning, we weren’t sure if we would be able to achieve the values we were aiming for. Getting to that last thousandth of a Cd value is the hardest part, but in the end, we exceeded our goals,” Lauterbach recalls.
The outstanding result was achieved primarily through “excellent teamwork between us (Aerodynamics experts) and our colleagues in Design. We all pulled together. From the beginning of the project, the Designers shared their drafts with us so that we could provide initial aerodynamic evaluations. In an iterative process – firstly using virtual simulations and later the physical model in the wind tunnel – we went on to optimize the basic vehicle body.
In particular, the basic proportions with the slim greenhouse and the sloping roofline contribute to good aerodynamics.”
Lauterbach and Ghelfi devoted considerable time to working on the details with their colleagues in the Design team. Ghelfi: “In all, we ran around 2,800 simulations on the car and spent countless hours in the wind tunnel and in meetings collaborating with surface experts and designers. For example, air curtains are used to improve the airflow around the front of the car. The outside edge of the air curtain intake protruded somewhat, which impeded the airflow. Millimeter by millimeter, we reached a compromise that ultimately worked out for both sides.” Lauterbach adds: “Another example is the rear track width. Our team would have liked it to be narrower. Together, we found a solution that brought out the best in terms of design, dimensions, and aerodynamics.” Ghelfi: “Regarding aerodynamics, the aero bezels were particularly important. The lateral breakaway edges on the rear of the A6 Avant e-tron made it possible to achieve a clearly defined flow stall. They are significantly larger than in other Audi cars. Working in the wind tunnel with our Design colleagues, we carefully pored over each side's respective arguments and strived to find the best solution. The result is that the aero bezels alone improve the range by 0.008, equivalent to eight kilometers. That’s a significant advantage to come from a single design detail.”
“Looking at the car overall, neither side had to make any major compromises. When all was said and done, and I called my colleague in Design to tell him that together we had achieved the Cd value of 0.21 for the A6 Sportback e-tron, he could hardly believe it,” recounts Lauterbach proudly.