The euroFOT project aims to test eight in-vehicle safety systems through field operational tests involving over 1500 drivers. To rigorously and practically evaluate the systems' impacts on safety, efficiency, and the environment, the project developed a methodology balancing experimental methods and real-world testing. This involved defining performance indicators, events, and situational variables for consistent analysis, as well as an experimental design addressing participant selection, study environments, and system exposure conditions. The methodology framework ensures comparable evaluations while allowing flexibility tailored to each field test.