Fuel efficiency refers to how effectively a vehicle converts fuel into distance traveled. It is commonly measured in miles per gallon (MPG) or liters per 100 kilometers (L/100 km). Higher fuel efficiency means a vehicle can travel further on less fuel, which can lead to cost savings and reduced environmental impact. Improving fuel efficiency can be achieved through various methods, such as regular vehicle maintenance, proper tire inflation, and adopting efficient driving habits. Additionally, advancements in technology, such as hybrid and electric vehicles, contribute to better fuel efficiency by using alternative energy sources and optimizing engine performance.