What is necessary for a vehicle to move?

For a vehicle to move, traction between the tires and the road surface is essential. Traction is the frictional force that allows the tires to grip the roadway, enabling the vehicle to start moving, maintain speed, and change direction safely. Without sufficient traction, a vehicle may slide or skid, especially in adverse weather conditions or on uneven surfaces, regardless of the engine power or fuel available.

Having a full tank of gas, passenger weight, or an engine operating at a certain temperature may impact the vehicle’s performance but are not directly necessary for initiating movement. A vehicle can technically drive with very little fuel (assuming there is enough to power the engine), and while weight can affect handling and performance, it is not a requirement for movement itself. Additionally, an engine can function at various temperatures without impairing the vehicle's ability to move, as long as it is operational. Thus, traction is the fundamental requirement for a vehicle to effectively and safely move forward.