Which of the following factors does not influence vehicle handling?

The factor that does not influence vehicle handling is the driver's mood. While a driver's mood can affect their decision-making, attention, and overall performance behind the wheel, it does not have a direct impact on the mechanical aspects of how a vehicle handles on the road.

In contrast, tire pressure plays a crucial role in handling characteristics, as under-inflated or over-inflated tires can compromise traction and stability. Road surface conditions, such as whether the road is wet, dry, or uneven, also significantly affect how well a vehicle can grip the surface and maneuver safely. Additionally, the speed of the vehicle influences handling because higher speeds may require longer stopping distances and can alter the dynamics of how a vehicle turns or reacts to road conditions. Each of these factors directly relates to the physics of driving and vehicle performance, making them critical to understanding vehicle handling.