## 3 WLTC-Based Analysis of Study Results  
### Energy Performance  
Analysing the vehicle load data (obtained from the load bench, Figure 2b) and the internal combustion engine load data (derived from the ICE ECU, Figure 2b), it is observed that the main trends in the vehicle and ICE loads are consistent across all driving scenarios (using fuels E0, E10, and E70). However, there is a slight difference in the maximum loads experienced by the ICE. These load differences are attributable to the specific operation of the hybrid drive's electric motor-generators. At higher battery charge levels, the electric motor generates more of the torque required to drive the vehicle, thereby reducing the load on the internal combustion engine. Conversely, when the battery is discharged, the load on the internal combustion engine increases, as its energy is used to propel the vehicle and to power the alternator and recharge the battery. This is corroborated by the graphs, which indicate that the load on the ICE is lower than the vehicle load during acceleration, while it is higher during low-speed, steady driving (Figure 2b). During braking (under negative load conditions), some kinetic energy is recuperated and converted into electricity to recharge the batteries. The observed instantaneous variations in ICE load during the same test phase when using different fuels do not significantly affect the overall WLTC test results. This is because the battery is quickly recharged under optimal conditions, and its energy is immediately utilised to assist in vehicle propulsion. During a test cycle, the battery undergoes multiple charge-discharge cycles that do not occur simultaneously. The uniform energy demand on the engine is evidenced by the calculated work performed by the ICE per WLTC cycle, which was consistent across all test cases, \(W_{ICE\_E\_WITC}\approx 4.412\) kWh, or the average distance travelled per 1 km 0.190 kW\(\cdot\)h ICE energy. The engine's power output is regulated by adjusting the air-fuel mixture via the throttle. Depending on the power demand of the ICE, the throttle opening varies, influencing the intake air-fuel ratio and engine speed (Figure 3a). The graphs indicate that, when testing with different fuel mixtures, the throttle position and engine speed vary across certain modes and are significantly affected by the operation of the hybrid electric motor, as previously described. The average throttle opening during the WLTC cycle was calculated, revealing that using E10 and E70 fuel blends, compared to E0, resulted in a slight reduction in throttle opening. This reduction is attributed to the oxygen content in these fuels, which requires less air for combustion. At the start of the WLTC tests, the engine was preheated, and the coolant temperature was 85 \({}^{\circ}\)C in all cases (Figure 3b). During testing, the engine-temperature-control system maintained the coolant temperature within a range of 87-99 \({}^{\circ}\)C, depending on the engine load and the cooling intensity regulated by the thermostat and the ECU. The exhaust gas temperature upstream of the catalytic converter at the start of the tests ranged from 249 \({}^{\circ}\)C to 286 \({}^{\circ}\)C, while downstream of the catalytic converter, it ranged from 230 \({}^{\circ}\)C to 274 \({}^{\circ}\)C (Figure 3b). As the vehicle speed and engine load increased in the low-speed mode (I), the exhaust gas temperature rose to approximately 600 \({}^{\circ}\)C upstream of the catalytic converter and around 400 \({}^{\circ}\)C downstream. However, the exhaust gas temperatures of the fuel blends E10 and E70 upstream of the catalytic converter were lower than those of pure gasoline (E0). Due to its greater latent vaporisation heat, the higher bioethanol concentration in the blends reduces the intake temperature, leading to lower combustion and exhaust temperatures [38]. Additionally, the increased thermal efficiency of these blends contributes to a reduction in the exhaust temperature.