This paper presents the results from a preliminary study where a wearable consumer electronic device was used to assess driver's state by capturing human physiological response in non-intrusive manner. Majority of state of the art studies have employed medical equipment drivers' state evaluation. Despite the potential gain in road safety this method of measuring physiology is unlikely to be accepted by private vehicle consumers due to its invasiveness, complexity, and high cost. This study was aiming to investigate possibility of employing a consumer grade wearable device to measure physiological parameters related to cognitive workload in real-time while driving i.e., drivers' heart rate. Furthermore, validity of captured heart activity metrics was analyzed to determine if wearable devices could be embedded into driving at its current technological state. The driving context was reproduced in desktop driving simulator, with 14 participants agreeing to take part in the study (μ = 28, σ = 8.5 years). Drivers were exposed to various road types, including pure Motorway, Rural, and Urban scenario modes. An accident was simulated in order to generate sudden cognitive arousal and capture participants' physiological response to the generated distress. It was found that a smartwatch is capable of reliable heart activity tracking in driving context. The results, supporting the relationship between cognitive workload level, generated by various complexity driving tasks, and Heart Rate Variability, were also presented.