With tighter environmental regulations, as well as political and public opinion pressure, the reduction of automotive polluting gas emissions is subject to intense debates and interests. Before a potential transition to full electrical vehicles as the long term solution, the reduction of mass remains of prime importance to permit direct reduction of emissions in internal combustion engine (ICE) vehicles. In addition to the challenges of structural integrity and safety issues, the acoustical and vibration performance of vehicles can be greatly influenced by mass reduction. This article presents a case study of lightweight design of an automotive door with a high strength steel thin gauge outer panel. An experimental comparison between a reference and a lightweight door was conducted in a complete vehicle, allowing assessing the potential effect of the mass reduction on the acoustic and vibrational performances. Several conditions were assessed: rolling on different surfaces, transient events such as heavy vehicle crossing and door closing events. The comparison method included the determination of main transfer paths on the full vehicle. The study indicated that the different acoustic and vibration performances of the vehicle were preserved.