This paper presents a vehicle-scale multichannel automotive audio demonstrator based on piezoelectrically actuated flat-panel loudspeakers (FPLs) integrated into existing cabin surfaces. The proposed architecture combines piezoelectric driven radiators embedded in headrests, front and rear doors, and an OLED center console with a conventional electrodynamic subwoofer for low-frequency extension, enabling full-band reproduction in a hybrid configuration. Operating frequency bands are assigned from electroacoustic characterization of each radiator and implemented through dedicated crossover design and DSP tuning. The system is analyzed through numerical simulation and evaluated experimentally in a prototype vehicle using AES automotive assessment procedures, objective electroacoustic indicators, and perceptual evaluation through Multi-Dimensional Audio Quality Score (MDAQS) metric. Results show that surface geometry, actuator placement, and time alignment improve in-cabin sound field distribution and directivity. After tuning, spectral balance improves and impulsive distortion artifacts are no longer evident, with corresponding enhancements in perceived timbre and overall quality. However, maximum output level remains constrained by the subtractive equalization required to control distortion and spectral balance. Overall, the study demonstrates the feasibility of hybrid piezoelectric--dynamic automotive systems, highlighting their packaging advantages and potential for reduced electrical power consumption while identifying the remaining limitations in low frequency capability, distortion performance, and achievable Sound Pressure Level (SPL).
