From shifting gears to changing modes: The impact of driver inputs on plug-in hybrid electric vehicle energy use & emissions

Abstract

This study measures the energy use and emission impacts of driver-induced changes to drivetrain configurations, known as drive modes. Drive modes allow drivers to alter their vehicles’ operating characteristics including propulsion energy sources, responsiveness of the steering wheel/accelerator pedal, etc. Plug-in Hybrid Electric Vehicles (PHEVs) can use energy from a combination of a battery and a fuel source to propel themselves, so drive modes that can shift vehicle propulsion power sources can directly impact energy usage and emissions in these vehicles. This study examines the use of drive modes in PHEVs. We use empirical, on-road vehicle data to explore whether drivers are using drive modes as intended by vehicle manufacturers and to develop a regression model and engine start analysis to quantify the impact of mode usage on PHEV energy efficiency and emissions. We find that incorrect use of drive modes leads to a 15–30% increase in energy usage and higher engine start emissions.