What does torque measure in a vehicle?

Torque measures the twisting force that an engine produces, which directly relates to the engine's ability to move the vehicle. It is essentially the power that the engine generates to accelerate the vehicle from a standstill and maintain its speed against resistance such as gravity and wind drag. Higher torque values typically mean better performance when it comes to moving heavy loads or navigating steep inclines, making it a crucial factor for commercial vehicles where power and load capacity are critical.

The other options address different aspects of vehicle performance or characteristics. Engine speed refers to how fast the engine is running but doesn't indicate how well it can move the vehicle. The weight of the vehicle impacts how much torque is needed to move it but is not a measure of torque itself. Fuel efficiency concerns how effectively fuel is converted into power, not the measurement of force that torque provides. Thus, choosing the option that recognizes torque as a measure of an engine's ability to propel a vehicle captures its essential role in vehicle dynamics.