Driver posture and ergonomics play a critical role in ensuring safety, comfort, and long-term health sustainability for vehicle operators. Poor posture and fatigue significantly impair reaction times, increasing accident risks. This study investigates postural deviations, fatigue effects on reaction time, and ergonomic validation to mitigate these risks. Driver posture health was assessed using video-based observation, manual data collection, and ergonomic benchmarking following ISO 2631 and SAE J826 standards. Results indicate that fatigue directly correlates with postural misalignment, leading to forward head tilt, lumbar strain, and cognitive fatigue. Manual posture assessments and seating ergonomics evaluations were identified as critical factors in reducing discomfort and enhancing driver performance. Findings show the necessity for real-time posture tracking in order to boost safety and productivity in driving. Additional research should explore the design of the vehicle seating to provide ergonomics improvements to posture correction as well as fatigue reduction.