Efficiency denotes a peak level of performance in which the fewest number of inputs are used to produce the greatest quantity of output. Reduce the quantity of superfluous resources utilized to create a particular result, including human time and energy. The fewer resources you use the more efficient you are. Efficiency is a broad concept that can be measured in many different ways. For example, research scientists measure the efficiency of solar cells by calculating how much electricity they convert into heat. Engineers design more efficient cars by making them lighter or using less material; thus requiring fewer efforts to build. As another example, the efficiency of an electric light bulb is calculated from the amount of energy it consumes while giving off light to the amount of energy contained in the battery before it is depleted. The higher the ratio between these two numbers, the more efficient the bulb is. There are several factors that determine a system's efficiency. One is the quality of materials used in its construction. A highly efficient machine would be one made with high-quality parts that are well designed and manufactured. Other factors include the type of engine or motor used, such as an internal combustion engine versus a battery electric vehicle motor; the size of the engine or motor relative to the load it must drive; and the technology employed to control fuel injection, ignition timing, and air intake filter capacity. Environmental factors such as temperature and humidity also affect engine efficiency.