This work introduces a new framework to study the acceptance of an autonomous vehicle by multiple passengers. By using a NeuroSky biosensor, automatic annotation of facial expressions can be achieved to eliminates most of the challenges we faced due to the manual methods of annotating subjects emotional data. Two application scenarios are presented: simulated and autonomous cars. The experiments with simulated car passengers show a high correlation between facial parameters and emotional states measured from attention and meditation indexes. Prediction accuracy are at high levels of 73.3% and 61.9% for some subjects attention and meditation respectively.