: In today's world due to the variety of products a lot of competition has been created between automobile manufacturers. Comfort and the security of the vehicle is the key to win the competition. For achieving victory, designers should be focused on these two parameters before production. In this thesis, the basic parameters of occupant’s comfort, the Noise, Vibration and Harshness in the Iranians class A vehicle have been investigated. In the first phase, structural vibrations have been simulated by modal analysis in the ABAQUS. In the second phase, the effect of engine vibrations and its transmission to the vehicle’s cabin was simulated and in the last phase, the car's acoustic environment has been added to the model and the behavior of acoustic pressure and sound pressure level within the driver's right ear was measured in three different modes with the engine running. First the vibrations were transmitted directly to the body, then the vibrations were transmitted with the intervention of viscoelastic dampener as the engine mount. The last mode was to add the ISD-110 viscoelastic material as the dampener to different parts of the car including roof, floor plate and doors and it was measured with the 2 nd mode included. The results were compared to the standards of Europe and had an acceptable result in the third stage. Finally, sound pressure level of four vehicles was measured and compared with each other Keywords: Noise, Vibration, Sound Pressure Level, Acoustic Pressure, Modal Analysis, Vibro-Acoustic Analysis for Class A vehicle