The research team of EMISIA and the Environmental Protection Department of Hong Kong have published their recent study:
Keramydas, C., Papadopoulos, G., Ntziachristos, L., Lo, T.-S., Ng, K.-L., Wong, H.-L. A., Wong, C. K.-L., 2018. “Real-World Measurement of Hybrid Buses’ Fuel Consumption and Pollutant Emissions in a Metropolitan Urban Road Network.” Energies, 11(10): 2569.
You may download the paper here.