With the development of electric motor vehicles, the domain of automotive sound design addresses new issues, and is now concerned by creating suitable and pleasant soundscapes inside the vehicle. For instance, the absence of predominant engine sound changes the driver perception of the dynamic of his car. Previous studies proposed relevant sonification strategies to augment the interior sound environment by bringing back vehicle dynamics with synthetic auditory cues. Yet, users report a lack of blending with the existing soundscape. In this study, we analyze acoustical and perceptual spatial characteristics of the car soundscape and show that the spatial attributes of sound sources are fundamental to improve the perceptual coherency of the global environment.