## 8 Results and Discussion
When the ORC system was included in the powertrain, the new fuel consumption was calculated to be 8.76 L/100 km, which is almost 1 L less per 100 km. On the other hand, on the NEDC, the results showed that the fuel consumption without the ORC system was 8.79 L/100 km, while when the ORC system was included in the analysis the new fuel consumption was 8.07 L/100 km. The difference between these two values is almost 0.8 L/100 km. The final driving cycle test was the US06, giving a fuel consumption of 10.57 L/100 km without the ORC system. When the ORC system was added in the analysis, the improved fuel consumption was decreased to 9.84 L/100 km, which is almost 0.7 L/100 km less. This driving cycle is more aggressive than the previous two, which is why the powertrain reached higher fuel consumption values in comparative terms to NEDC and FTP-75. Moreover, the results from the driving cycle analysis can assist the understanding of how the ORC system cooperates with the engine under different loads, accelerations, and decelerations. The three selected driving cycles constitute a representative example of driving regulations in use today and which were required to validate HEV performance with the novel component (ORC WHR system). In Figure 5h the bar charts illustrate the differences in fuel consumption between the original HEV engine and the ORC-equipped equivalent in order to minimize fuel consumption. Furthermore, the percentage difference is calculated, so that the absolute difference of the improved powertrain can be differentiated. This bar chart includes information for all three of the driving cycle tests and presents the exact amount of burned fuel per 100 km of driving. It can be noticed that in all of the driving cycle scenarios, the fuel consumption was decreased after the implementation of the ORC system. The largest reduction was found to be in the FTP-75 driving cycle and the calculation of the absolute percentage difference showed a 10% lower fuel requirement for 100 km. The NEDC required the least amount of fuel, as it is not as aggressive as the other two cycles. Moreover, in this driving cycle the ORC system improved the fuel consumption by 8%, which is a significant reduction if the strict European regulations are taken into consideration. Finally, the US06 driving cycle required the most fuel overall, but the ORC system managed to lower the fuel consumption of the vehicle by 7%, which resulted in a drop of fuel consumption below 10 L/100 km. A closer look into the three driving cycles was required to reveal the driving strategy needed in order to maximize the powertrain performance in the electric hybrid vehicle. Taking into account the three major hybrid operation modes, which are the traction mode, braking mode, and coasting mode, the driver can be guided in how to handle the accelerator pedal, the braking pedal, and the clutch pedal to maximize the efficiency of the overall vehicle. As far as the NEDC is concerned, it can be identified that it consists of numerous accelerations and decelerations, and the average cruising speed is 60 km/h. This driving cycle profile can exploit the braking and coasting operation modes of the hybrid configuration to gain advantages regarding the fuel consumption of the vehicle. During the decelerations the brake should be lightly applied and this will lead to the battery being charged by dissipating the braking energy and, hence, more power can be delivered to the wheels during the acceleration zones. Moreover, the driver can use the coasting mode, while no brakes or throttle are applied, before reaching the deceleration zones and prevent, in that way, the engine from burning fuel in a non-beneficial manner. The FTP-75 driving cycle has a complicated profile of accelerations and decelerations, which makes it difficult for the driver to adopt the optimum driving strategy. However, as there are multiple fluctuations in the speed profile of this cycle, the driver can exploit the braking mode to charge the battery of the hybrid setup.