*5.4. Comparative Energy Consumption Results*

Table 5 gives the energy consumption simulation results for the PHEV and BEV fleets configured in the previous two sections, as well as HEV and CONV fleets, all simulated over the full recording period. The HEV fleet can reduce the fuel consumption by around 50% compared to CONV fleet, owing to regenerative braking, switching the engine off in low speed conditions and placing the engine operating points in the high-efficiency region (Section 4; see also Table 3). Using the PHEV buses provides additional fuel savings, i.e., the fuel consumption reduction compared to CONV case is around 70%. This is due to the use of electricity coming from grid by means of fast charging at end

stations. The PHEV fleet electricity consumption equals almost 50% of what is consumed by BEV fleet, which is owing to a relatively low portion of operation in the CS mode (25.5%).


**Table 5.** Fuel and electricity consumption per fleet type for full five-month period.

\* Ref stands for referent case, and values in brackets represent relative differences with respect to referent case.

The COM also calculates the well-to-wheel CO2 emissions taking into account the data on CO2 emissions of power plants, as used in [28] for the cases considering coal, natural gas and renewable energy production. The HEV vs. CONV fleet CO2 emissions reduction is around 50%, while in the cases of PHEV and BEV fleets, the reduction is from 30% to 65% and from 30% to 93%, respectively, where the lower and higher margins correspond to coal and renewable energy production scenarios.
