DescriptionThe study investigated drivers’ overtaking behavior in partially automated vehicles and conventional vehicles under different traffic density conditions. Twelve participants “drove” a simulated vehicle on a 10-mile straight, two-way rural interstate highway in 4 scenarios (2 (traffic density: Low, High) × 2 (vehicle type: Partially automated vehicle, Conventional vehicle)) in random orders. Participants’ driving performance, eye movement, brain activity, and workload were collected and analyzed. Results indicated that vehicle type significantly affects speed standard deviation, pupil dilation, and workload. Results also showed that traffic density significantly affects average speed and workload. The findings should help improve the design of automated vehicles and thus improve traffic efficiency.