Treharne, W., Badger, C., Martin, D., Mansour, M. et al., "Economy Mode for Electrified Vehicles," SAE Int. J. Alt. Power. 6(1):84-94, 2017, doi:10.4271/2017-01-1159.
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. Measures of the fuel economy improvements were developed, as were tests to represent real-world driving conditions. The final package of potential fuel economy changes was tested on several Ford Hybrid vehicles with results demonstrating the net improvement to vehicle fuel economy. The Economy Mode functionality was deemed to be effective and it entered vehicle production during the 2016 model year on the Ford Fusion Hybrid, Ford C-MAX Hybrid, and Lincoln MKZ Hybrid vehicles under the name of EcoSelect.