During vehicle development, aerodynamics, design and package must not be regarded separately. There is strong interdependence between the three areas which has to be taken into consideration. When speaking of the aerodynamic design of the outer body shell, physical regularities assume primary importance. Techniques and customer requirements play an important role in packaging. The design of new models is determined by the exterior design of the vehicle and can be considered a less rational criterion.
The relationship between Aerodynamics engineers and Designers was marked by a mutual lack of understanding for a long time. The first aerodynamics engineers who worked on automobiles came from the aircraft industry. Since aerodynamics play a totally different role there when compared to cars, the engineers developed extreme forms which compromised technical issues related to the automobile, for example, the positioning of the engine.
The Designers on the other hand prioritised aerodynamics as an inconvenient side issue. In the best case, they saw the expression of a styling-trend in aerodynamics, but had no understanding for the technical implications of aerodynamics.
The conflict between art and physics first saw a solution when the automobile manufacturers integrated both aerodynamics engineers as well as vehicle engineers in the same development teams. The aerodynamics engineers then identified how strongly the freedom for design is limited by technical demands as well as legal regulations. Similarly, the designers were made conscious of aerodynamics as a comprehensive science.
Aerodynamics assume an increasing value under the obligation to reduce fuel consumption. The economy of a vehicle can, not only be described quantitatively, but also by its exterior design. During vehicle development, the aerodynamic targets must be clearly defined. The final form of the outer body shell is the result of numerous iterative processes undertaken by specialists in design, aerodynamics and package departments.
The basic conditions for the creation of styling models are indicated to the designer in form of a specification plan. This contains specifications of basic dimensions in longitudinal and transverse sections as well as all necessary specifications for the interpretation and design of the interior. The target of such a plan is to limit the freedom (of design) of the designer only to those areas where legal regulations, ergonomic requirements or functional restrictions permit. This contains essential contours in longitudinal and transverse section for necessary free space and the required space for the entire vehicle. Further it represents the border outlines for head movement of the passengers as well as their positioning as result of an ergonomically optimised design of the interior.
The legal regulations from the point of view of the design of the outer shell includes for example, positioning specific to different regions:
· Positioning of headlights, brake lights, tail lights, driving direction indicators, rear fog light and back-up lamp, lateral marking lights
·         Bumper height
·         License plate
·         Wheel covers
·         Visibility conditions of the driver
Minimum radii for projecting components of the exterior surface