The idling of fuel efficiency -- A Chicago Tribune Story by Rick Popely and Jim Mateja


Actually, the difference between fuel efficiency and fuel economy must be understood clearly. Fuel efficiency is a measure of how effectively a vehicle uses the energy from fuel, whereas fuel economy is what consumers measure as they drive on the road, or what manufacturers report to the government, i.e., the miles per gallon value. While fuel efficiency of cars and light trucks continues to increase, the overall fleet fuel economy has remained flat since the late 80’s.