Mileage efficiency of cars

Abstract

This paper proposes a mileage efficiency metric to enable direct comparison of energy efficiency and greenhouse gas emission of cars for various vehicle mass, fuel type, vehicle make, vehicle technology, road infrastructure, and drive schedule. This metric allows a unifying measure of vehicle mileage and fuel consumption regardless of the above factors. The proposed mileage efficiency metric is based on the concept of an ideal car (IC), which is defined as the one without internal or external losses; or an ideal powertrain car, which is defined as the one without internal losses. Mileage efficiency is defined as the ratio of a real-world car (RWC) fuel economy (in miles per gasoline gallon equivalent or mpgge) to that of an ideal car. As such, mileage efficiency is able to attribute efficiency loss of a RWC to internal and/or external losses. It is shown that mileage efficiency depends on car design and shows how good or bad RWCs are relative to ICs. The paper also highlights the importance of good road infrastructures in reducing transportation fuel consumption independent of fuel efficiencies of cars. This work provides a fundamental framework to set government policies and incentives for vehicle technology, alternative fuel choice, and infrastructure investments. • Mileage efficiency is the mileage ratio of a real-world car to an ideal brake-loss counterpart. • An ideal brake-loss car is one that has no powertrain or rolling friction and drag losses. • Mileage efficiency measures the energy efficiency potential of a real-world car. • Mileage efficiency depends on vehicle size, technology, fuel type, and infrastructure. • A mileage efficiency-based policy making framework is discussed.