From passenger perception to vehicle-level requirements: A state-of-the-practice review and roadmap for NVH, ride comfort, and motion sickness in electrified and automated vehicles

Passenger comfort has become an increasingly important consideration in automotive development, particularly as electrification and automated driving reduce traditional powertrain noise and shift passenger attention toward vibration-, noise-, and motion-related discomfort. Existing comfort evaluation methods span both vehicle-perspective approaches based on objective measurements and passenger-perspective approaches relying on subjective assessment, biosignals, and surveys. However, the relationship between these perspectives and their respective roles in practical vehicle development are often unclear. This paper reviews comfort evaluation methods from both vehicle- and passenger-perspective viewpoints, with emphasis on buzz, squeak, and rattle (BSR), structure-borne road noise, ride comfort, odor, fatigue, and motion sickness. The strengths and limitations of each class of methods are discussed in the context of automotive engineering practice. The review focuses on linking passenger-perceived discomfort to objective, repeatable vehicle-level metrics that can inform subsystem requirements. A requirements-oriented framework is presented to link subjective complaints to surrogate evaluation indices, test protocols, and subsystem-level design targets for vehicle development. Representative metrics include band-limited sound pressure levels, frequency-weighted root-mean-square acceleration for whole-body vibration (WBV) assessment, and motion sickness dose value (MSDV). Selected assessment steps are illustrated through industrially relevant examples. These include a seatbelt-related BSR evaluation process with force reconstruction and a vibration-based approach for assessing ride comfort and motion sickness tendency. By emphasizing deployable metrics and development relevance, this study aims to support systematic and efficient comfort-oriented vehicle design.