To drive safely, it is essential that the **seat and backrest are properly adjusted**. This ensures that the driver can reach the pedals without straining the ankles and that the legs are slightly bent, which is crucial for maintaining control of the vehicle. Additionally, the backrest should allow the driver to reach all controls effortlessly, with the back fully supported by the seat.

Placing a towel on the seat can alter this optimal position, as it could change the height or inclination of the seat, affecting the driver's posture. This can lead to a dangerous situation known as the **submarining effect**, where the driver may slide under the seatbelt in the event of a sudden stop or accident. This sliding can increase the risk of serious injuries, as the seatbelt will not be able to properly restrain the driver.

Therefore, although it may seem like a solution to protect the seat or make it more comfortable, placing a towel on the seat **can promote the submarining effect**, compromising the driver's safety.