Fuel Efficiency Benefit for Electrified Vehicles from Advanced Spark-ignition Engine Technologies

Worldwide fuel consumption regulations are becoming more and more stringent. As a result, car companies are looking at a wide portfolio of component technologies, including engines, transmissions, and electrification. This study examined fuel consumption reductions offered by a collection of advanced spark-ignition (SI) engine technologies using full-vehicle simulations. High-fidelity engine models were developed to simulate Variable Valve Lift (VVL), Turbocharging and Downsizing (T), and Gasoline Direct Injection (DI) technologies in an incremental manner through an accumulative technology pathway. Measurements from these models were used to build full-vehicle simulations for each of the technologies across a spectrum of vehicle powertrain configurations with increased electrification. Each vehicle component was algorithmically sized to meet common performance criteria to ensure uniformity and comparability. The effects of vehicle hybridization and electrification on the technology fuel reductions while transitioning from conventional to mild, full, and plug-in hybrid configurations were investigated. Conventional vehicles were found to attain the highest overall benefits, while mild and full hybrid vehicles attained lower benefits. A negative correlation was found between engine technology benefit and vehicle hybridization. Over the pathway, cycles, and configurations investigated, average benefits for DI were found to be 8.0%; VVL, 3.4%; Turbocharging and downsizing, 9.7%; and downsizing from 1.6 L to 1.2 L, 2.7%.