The driver’s seat lower cushion in my 2023 Toyota Highlander provided inadequate support during normal driving, particularly on the left side of the seat cushion where support for my left leg and hip area appeared insufficient. This caused uneven seating posture, increased discomfort, pressure, and difficulty maintaining a proper driving position during extended periods of driving. The seat became increasingly uncomfortable during prolonged use and caused pain, numbness, and difficulty maintaining a proper driving position. I am a professional driver and spend many hours operating the vehicle. Over time, the lack of support contributed to left-sided sciatica symptoms that required medical evaluation and physical therapy. Medical records document that prolonged sitting in the vehicle aggravated my condition and limited my ability to sit and drive comfortably. An independent upholstery specialist inspected the seat and determined that additional foam had to be added to the driver’s seat lower cushion to improve support and comfort. After the modification, the seat became significantly more comfortable. This indicates that the original seat cushion support may be inadequate. I believe this condition may affect other vehicles of the same model and should be investigated as a potential safety concern because it can affect driver posture, comfort, concentration, and safe vehicle operation during extended driving.