Recently automotive software has been more complex and needs to be reduced its development time. Software testing of its functionalities and performance should be conducted in an early development phase to reduce time to market and the development cost. Software functional testing can be performed through simulating the hardware, but it is not guaranteed that evaluation of real-time performance using simulation has enough accuracy. Real-time performance can be precisely evaluated with hardware-in-the-loop simulation, but it costs time and effort to set up hardware for testing. In this paper, we suggest a testing system that can evaluate functional requirements and real time properties with a general-purpose development board in the early development phase. In addition, we improve reusability of the testing system through modularized and layered architecture. With the proposed testing system we can contribute to building reliable testing system at low cost without difficulty.