This paper presents three-dimensional investigations of flow fields in the passenger compartment model using the Computational Fluid Dynamics (CFD) and Particle Image Velocimetry (PIV). Two ventilation types are used in which the fluid flow is discharged from the windshield defroster grilles as well as the IP vents and this represents the panel mode. A fifth-scale model of a passenger compartment, which includes a driver, is considered. The flow fields from both discharges and their effects on passenger comfort are discussed and examined in detail, particularly the regions that surround the driver and passenger seats.