Since the majority of the innovative trends in automotive industry today are based in advanced electronics technology, mastering the EMI (Electromagnetic Interference) between embedded electronic subsystem and the EMC (Electromagnetic Compatibility) features of a vehicle in its early design phase becomes one of the crucial technical challenges faced by all automotive manufacturers. Even if all electronic subsystems in a vehicle are validated under the EMC standards, the integration between them may create numerous points of potential hazards that affects the total electromagnetic behavior of the entire system, hazards that can be detected only once the first complete prototype is available, and whose resolution at this phase of the process is very time consuming and expensive. This paper presents the state of the art regarding electromagnetic numerical analysis using Ansoft HFSS (High Frequency Structure Simulator) tool and a parallel HPC (High Performance Computing) consisting of numerous computer nodes connected to a network. An application of this approach to a vehicle modeling is presented. Adaptations to CAD (Computer-Aided Design) models are proposed in order to improve CAE (Computer-Aided Engineering) analysis and save computer effort with the objective to reach a correct level of industrial efficiency. EMI between subsystems are investigated using field solvers and a SI (Signal Integrity) analysis is performed in a wiring harness transmitting a random CAN J1939 standard signal. A complete analysis on EMI and EMC properties is performed, and a conclusion concerning the practical use of numerical simulation at early stages of the vehicle design is proposed.