In collaboration with Volvo Cars, we presented a novel design tool to a large public of approximately three million people at the three leading motor shows in 2017 in Geneva, Shanghai and New York. The purpose of the tool was to explore the relevance of interactive audio-visual strategies for supporting the development of sound environments in future silent cars, i.e., a customised sonic identity that would alter the sonic ambience for the driver and by-passers. This new tool should be able to efficiently collect non-experts' sonic preferences for different given contexts. The design process should allow for a high-level control of complex synthesised sounds. The audience interacted individually using a single-touch selection of colour from five palettes and applying it by pointing to areas in a colour-book painting showing a road scene. Each palette corresponded to a sound, and the colour nuance in the palette corresponded to certain tweaking of the sound. In effect, the user selected and altered each sound, added it to the composition, and finally would hear a mix of layered sounds based on the colouring of the scene. The installation involved large touch screens with high quality headphones. In the study presented here, we examine differences in sound preferences between two audiences and a control group, and evaluate the feasibility of the tool based on the sound designs that emerged.