Coasting Technology for Real-World Fuel Economy Improvement of a Hybrid Vehicle

Automobile manufactures need to adopt new technologies to meet global CO₂ (carbon dioxide) emission regulations and better fuel efficiency demands from customers. Also, the production cost should be as low as possible for an affordable vehicle. Therefore, it is advantageous for OEMs to develop fuel efficient technologies which can be controlled by software without additional hardware costs. The coasting control is a fuel efficiency improvement technology that can be implemented by the change of vehicle software only. The coasting control is a technology that reduces the driving resistance (Deceleration) when the driver releases the gas pedal. This technology leads to reducing the energy required for the vehicle to drive and results in improving the real-world fuel economy. In an internal combustion engine (ICE) vehicle, the coasting state is achieved by changing the gear to neutral, and the effect has been discussed and clarified by many previous studies. On the other hand, in the coasting state of a hybrid vehicle, the regenerative energy to the motor is reduced while the driver releases the gas pedal. The coasting control of a hybrid vehicle tends to be perceived as deteriorating the fuel efficiency because the regenerative energy decreases. In this study, relations of the vehicle deceleration and the fuel economy (vehicle energy consumption) of a hybrid vehicle were studied quantitatively. In addition, we confirmed that the coasting technology was effective to improve fuel economy (reducing CO₂) based on the real-world big data.