Torque
Torque is best described as a twisting force. In an engine, the up-and-down motion of the pistons is converted into the rotary motion of the crankshaft using a conrod, producing an effective torque at the crankshaft's end. The transmission turns this torque into pulling power. The physical unit for measuring torque is the Newton-metre (Nm). Today's engines are designed to deliver as much torque as possible, both from low rev speeds and over a wide rev range. This makes for good in-gear acceleration and means you do not have to change gear as often, so saving fuel. An engine's performance characteristics can be seen from its output (kW or PS) and torque (Nm).