## 3 Results and Discussion
Figure 10: The brake power \(P_{B}\) of the internal combustion engine during WLTC simulation: I—Urban cycle; II—Medium-speed cycle; III—High-speed cycle; IV—Very high-speed cycle. The emission indicators of an SIE (\(E_{CO}\), \(E_{HC}\), and \(E_{NO_{z}}\)) using G100 and G95H5 fuels (Figures 12-14) across a wide range of engine speeds and loads were determined in the first stage of the study through experimental engine testing on a dynamometer. The emission trends of incomplete combustion products (CO and HC) and nitrogen oxides varied with changes in engine load and speed, but certain similarities were also observed. At low and moderate loads and speeds, CO emissions were relatively low due to the maintenance of stoichiometric air excess, ensuring efficient combustion (Figure 12). As engine loads approached maximum levels, the mixture was enriched, leading to a significant increase in CO emissions, especially at maximum speeds, as combustion time decreased. HC emissions consistently increased with rising engine speed and load (Figure 13) due to the greater amount of combustible mixture in the cylinder and the reduced combustion duration. Similarly to the case of CO, a sharp increase in HC emissions was observed when approaching maximum torque, and the air-fuel mixture was enriched [55]. Figure 11: Fuel consumption during the WLTC test using pure gasoline G100 and dual-fuel G95H5: I—Urban cycle; II—Medium-speed cycle; III—High-speed cycle; IV—Very high-speed cycle. The NO\({}_{x}\) emissions were determined by the combustion temperature in the cylinder and the air excess coefficient. It was observed that increasing the engine load resulted in a rise in NO\({}_{x}\) emissions (Figure 14). This was due to the greater volume of the air-fuel mixture in the cylinder (volumetric efficiency) caused by a wider throttle opening, which increased the combustion temperature in the cylinder. However, as engine loads approached maximum levels, a significant increase in NO\({}_{x}\) emissions (as seen in the cases of CO and HC) did not occur due to the richer fuel mixture and a lack of oxygen [54; 56]. In the second stage of the research, the engine emission data (\(E_{CO}\), \(E_{HC}\), and \(E_{NO_{x}}\)) were uploaded into the AVL Cruise(tm) numerical simulation software and used to determine the vehicle's emissions at individual WLTC points (instant emissions), based on specific engine speeds and loads. These point-specific emission data were then used to calculate the total emissions over the entire test cycle. Several researchers have published similar studies, but they used gas rather than petrol [57; 58]. Figures 15 and 16 show quite different trends in the emissions of incomplete combustion products (CO and HC). This is due to the different tendency observed in the CO and HC emission maps (Figures 12 and 13). The total emissions (kg) calculated using the AVL Cruise software were used to analyze the specific emissions (g/km) of the different driving phases (cycles) of the WLTC by dividing the total emissions by the distance travelled during driving mode. During the urban cycle (I), the CO specific emissions were low (0.38 g/km  
Figure 14: NO\({}_{x}\) emissions map: **(a)** G100; **(b)** G95H5. Figure 13: HC emissions map: **(a)** G100; **(b)** G95H5. for G100 and 0.30 g/km for G95H5) but increased significantly (\(\sim\)8 times) with increased engine load and the enrichment of the air-fuel mixture (3.0 g/km for G100 and 2.3 g/km for G95H5) at very high vehicle speeds (IV). The HC specific emission intensity at low load (I) is even slightly higher (0.85 g/km for G100 and 0.54 g/km for G95H5) compared to very high vehicle speeds (IV) (0.46 g/km for G100 and 0.30 g/km for G95H5), due to the fact that combustion is carried out at a lower temperature at low load, and therefore, the HC emissions are still high, even at idling speed. When analyzing carbon monoxide (CO) emission trends over the WLTC using G100 and G95H5 fuels, the addition of 5% hydrogen by mass to gasoline significantly reduced cumulative CO emissions.