The object of this paper is to develop a random vibration laboratory test specification for automotive subsystems using the Power Spectral Density (PSD) method. This development is based on the 150k mile field data collected from vehicle proving grounds. The simulated vibration bench test will be used to simulate the energy of the 150k mile field data. The developed specification will include 3 axis random vibration profiles of appropriate duration.The Power Spectral Density method converts the time-domain field data into the frequency-domain data. The Enveloped Energy method groups the similar road PSD profiles to produce a generic PSD profile. The Inverse Law allocates an adjusted duration to the desired PSD energy level. The Road Test Specification provides the duration time for the developed bench test. The n-Soft tool  is utilized for data reduction analysis.The Bench Test Specification of the Fuel subsystem is a pilot for this development. Tri-axial accelerations are recorded at three locations near mounted constraints of the fuel subsystem on the body side. The validation for the development is the duplication of field damage on the fuel subsystem in the laboratory test.