Depending on the category of a vehicle, an optimal seating position is realised exclusively in each case. In case of a sports car, aerodynamics demand a low roof height and this means a deeper seating position, while the internal dimensions of a truck's driver cab (smaller length but larger height) demand a very upright seating position.
With an increasing seating level, keeping the Heel Point constant, starting from the sports cars, cars, transporters and up to trucks, the SgRP moves higher while the Knee, Hip and the Elbow angles decrease. This implies that the seat adjustment range that can be selected gets smaller with an increase in the seating height, figure above.