As demand grows for new in-vehicle features, a large number of electronic control modules are being introduced in the automobile to increase passenger's comfort, safety, entertainment and overall performance. The performance parameters of features such as electronic power steering, engine management systems, anti-lock braking systems, airbag systems, transmission systems, navigation and entertainment systems are monitored and controlled by electronic control units (ECUs). Vehicle-level ECU testing for small hardware or software changes is not practical and it is expensive. Therefore, bench-level testing is an effective way to ensure ECU functionality, as long as the tester is able to effectively simulate vehicle conditions during the bench test.Bench-level testing involves use of either static or programmable simulators to simulate the required functionalities. The programmable simulator is generally a better tool than the static simulator because it is configurable. This paper gives an overview of how MATLAB "Simulink® model can be used to configure a programmable vehicle simulator. Simulink® is a powerful modeling tool that provides an efficient way of simulating the system under design. The modeled system can be converted into an executable which can be deployed on to the target hardware (simulator) and can be run in real time.This paper explains about how to configure the vehicle simulator for various functionalities using MATLAB -Simulink® model. This paper focuses on the following functionalities: vehicle interface, instrumentation support, supporting of periodic data acquisition (DAQ) using CCP (CAN calibration protocol) and XCP (universal calibration protocol), periodic data stimulation (STIM) using XCP, simulation of fault conditions to test the ECU, simulation of diagnostic test tool to read diagnostic trouble codes (DTC), simulation of power waveform test tool, replay vehicle logs on the hardware.The simulator is used to test the ECU in a laboratory, simulating the conditions that would occur if the ECU was in the vehicle and exposed to real driving scenarios. Real-time Vehicle logs can be replayed back on the ECU. When performing in-vehicle testing, testers must provide diagnostic services to read the fault and instrumentation tools to re-flash the software. In-vehicle tests also must account for battery supply variations, necessary diagnostics and have comprehensive vehicle logs to ensure test repeatability. MATLAB -Simulin® modeling can be used to simulate all such scenarios. This article explains simulation of functionalities mentioned above, using MATLAB -Simulink\R model.