The purpose of this study is to find out how the mental load varies among drivers in different driving environments, where the perceived stress will be compared with the biological stress while driving a car. Twenty-six experimental runs were performed where the driver drove a car in a real traffic environment. Test participants were both men and women between the ages of 20 and 48, where everyone who participated had a driving license. Galvanic Skin Response (GSR) was used to measuremental strain. After each run, the participants were asked to answer a questionnaire called NASA-TLX, a subjective multidimensional data load index. This is an evaluation tool used to measure the perceived workload. The participants’ self-assessment of the workload while driving was then compared with GSR data. The main result is that accessing the motorway and exiting the motorway means greater mental strain than the other driving environments. Data from GSR and NASA-TLX showed no difference, which means that the participants’ self-assessment is consistent with the physiological measure GSR.