## 2 Materials and Methods
### The Methodology of WLTC Numerical Simulation  
In the second part of this study, to comprehensively evaluate the impact of a hydrogen additive on the performance parameters of a spark-ignition engine operating on gasoline under simulated real-world driving conditions, a numerical model of a Nissan Qashqai J10 (Nissan Motor Co., Ltd., Yokohama, Japan) passenger car was developed using the AVL Cruise(tm) simulation software (Figure 6). The vehicle is equipped with a four-cylinder spark-ignition engine (HR16 DE) with a displacement of 1.598 dm\({}^{3}\), a maximum power output of 84 kW at 6000 rpm, and a maximum brake torque of 156 Nm at 4400 rpm. The vehicle's wheelbase length is 2630 mm, the frontal surface area is 2.32 m\({}^{2}\), the aerodynamic drag coefficient is 0.32, the curb weight is 1272 kg, and the maximum allowable weight is 1830 kg. The car features a five-speed manual transmission with the following gear ratios: 3.73, 2.1, 1.39, 1.09, and 0.89. The capacity of the fuel tank is 65 L, and the dimensions of the tires of 215/65 R16 are used in this model. According to the Worldwide Harmonised Light Vehicles Test Procedure (WLTP), based on the engine power-to-mass ratio (PMR) and the manufacturer-declared maximum vehicle speed, the WLTC driving cycle was assigned to \"Class 3b\". Vehicles in \"Class 3b\" have an engine power-to-mass ratio greater than 34 W/kg and a manufacturer-declared maximum  
Figure 6: The numerical model of the Nissan Qashqai J10 vehicle in AVL Cruise(tm) simulation software: 1—the main vehicle component Nissan Qashqai, 2—the naturally aspirated internal combustion engine HR16 DE, 3—friction clutch, 4—manual transmission, 5—final drive, 6—rear right wheel, 7—front right wheel, 8—rear left wheel, 9—front left wheel, 10—rear right brake disc, 11—front right brake disc, 12—rear left brake disc, 13—front left brake disc, 14—differential, 15—cockpit, 16—anti-slip control (ASC) system, and 17—monitor. speed of at least 120 km/h. The tested vehicle's maximum speed is 175 km/h, and its PMR is 66.04 W/kg. The WLTC simulation task for the vehicle was created in a dedicated folder within the simulation software by inputting the driving cycle data (time-speed-load). During the numerical simulation, real-world driving conditions were modelled for 30 min across four distinct modes:  
1. Urban cycle: a maximum speed of up to 56.5 km/h, average speed of 18.9 km/h, duration of 589 s, and distance of 3.09 km. 2. Medium-speed cycle: a maximum speed up of to 76.6 km/h, average speed of 39.5 km/h, duration of 433 s, and distance of 4.76 km. 3. High-speed cycle: a maximum speed of up to 97.4 km/h, average speed of 56.7 km/h, duration of 455 s, and distance of 7.16 km. 4. Very high-speed cycle: a maximum speed of up to 131.3 km/h, average speed of 92 km/h, duration of 323 s, and distance of 8.25 km. Environmental conditions during the simulation were set as follows: an ambient temperature of 23 \({}^{\circ}\)C, relative humidity of 50%, and atmospheric pressure of 1.013 bar. As shown in Figure 7, during the WLTC simulation conducted using AVL Cruise(tm), the tested vehicle travelled a total distance of 23.27 km in 1800 s while maintaining the prescribed speeds. An analogous driving cycle was simulated with the vehicle operating on both G100 and G95H5 fuels. In this study, the vehicle's WLTC was simulated using the AVL Cruise(tm) software. In the near future, after installing an additional hydrogen fuelling system in the vehicle, real-world driving tests are planned. The experimental investigation of the WLTC cycle will involve the use of a chassis dynamometer, fuel (gasoline and hydrogen) mass metre, air mass metre, gas analyser, and other equipment. Using data obtained from the experimental tests, the vehicle's energy and environmental performance indicators will be calculated [49], and the validation of the numerical simulation results presented in this article will be conducted.