While evaluating the performance of a new vehicle, physical specifications and likely performance parameters of the vehicle are the only data known to the test driver. Effects of various ground irregularities encountered as shocks and vibrations that often catapult driver and vehicle into air can cause quantitative physiological changes associated with psychological implications on the subject driver. A test setup was developed at National Centre for Automotive Testing of VRDE, to study the response of test drivers on tracks containing irregularities. A medium crosscountry truck was used for the experimentation. The object of this paper is to study and exploit the results obtained from this test and examine whether they lead to some conclusion regarding effect of vibration spectra on physiological response of subject driver.The test results indicate that younger drivers with ideal height and weight combination showed lower level of stress symptoms. The clinical parameters recorded, however, showed almost identical levels before and after trials. Older and over weight driver showed lower tolerance capacity in form of giddiness, headache, throwing of gastric juice in the mouth. Discomfort and pain were paramount in the lower back region with tightening of calf muscles and pain over various joints. The clinical parameters were not significantly altered, however, showed slight increase in their pulse and respiration rate.