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Gasoline particulate filters (GPFs) are extremely effective at reducing tailpipe emissions of particulate mass and particulate number. Especially in the European and Chinese markets, where a particulate number standard is legislated, we see gasoline particulate filters being deployed in production on gasoline direct injected engines. Due to the high temperature in gasoline exhaust, most applications are expected to be passively regenerating without the help of an active regeneration strategy. However, for the few cases where a customer drive cycle has consistently low speed over a long time frame, an active regeneration strategy may be required. This involves increasing the exhaust temperature at the GPF up to around 600 degC so that soot can be combusted. We compare two different ways of achieving these temperatures, namely spark retard and air fuel ratio modulation. The former generates heat in the engine, the latter generates heat in one or more catalysts in the exhaust system.

Hybrid and Electric vehicles present special challenges when developing a customer-selectable Economy Mode, as the vehicles are already energy-efficient by design. This paper analyzes the sources of sub-optimal fuel economy in: energy generation, vehicle usage, and customer usage. The paper first reviews the effects on customer acceptance from other implementations of Economy Mode, using “Things Gone Wrong” data from customer surveys on competitive vehicles. This information was used as lessons learned for the new design. The paper then discusses which changes to vehicle functionality could be implemented to improve fuel economy while maintaining acceptable vehicle performance, along with acceptable noise, vibration, and harshness objectives. The vehicle parameters studied in this paper include: 12 V loads, engine operating commands of torque and speed, EV operating limits, customer demand inputs, regenerative braking, cruise control operation, and climate control function.