## 2 Materials and Methods
### Methodology for Calculating Energy Performance and Emissions in the WLTC Cycle  
This study's aim was to evaluate a vehicle's energy and environmental performance using different fuel blends. This evaluation was based on various indicators recorded by multiple measuring devices during the tests. During the WLTC test cycle, different devices collected data at varying frequencies. Vehicle load bench data, including the speed, acceleration, load, and fuel consumption, were recorded at a rate of 10 times per second (f = 10 Hz). Exhaust gas concentrations (O\({}_{2}\), CO\({}_{2}\), CO, HC, NO\({}_{\rm x}\)) were recorded once per second (f = 1 Hz). In contrast, data from the ECU were recorded at a much higher frequency of 58 Hz (f = 58 Hz). To ensure consistent analysis, all data needed to calculate energy and emissions were aligned to the same frequency. Therefore, all data recorded at frequencies greater than 1 Hz were converted, in Microsoft Excel, to an average over a one-second interval for the entire 30 min (1800 s) WLTC cycle. After processing the WLTC test data as described, the data were synchronised to align the vehicle speed, ICE performance parameters, and emissions over time. This synchronisation was necessary because the data streams from various measuring devices extended over a period longer than 1800 s, and some data, such as those from the gas analysers, were delayed due to the specific characteristics of their operation. The vehicle and engine data indicated that the vehicle remained stationary for the first 9 s of the test cycle, and the engine was not running. Consequently, the gas analyser data were adjusted and aligned so that the recorded increases in pollutant concentrations corresponded to the engine's operation, beginning on the same row in Excel, creating a continuous 1800 s data  
Figure 2: Various settings during WLTC using different fuels: (**a**) vehicle speed and distance travelled; (**b**) vehicle load, ICE load, and work performed by the ICE. stream. Once the data were synchronised at the start of the study, the end of the study was reviewed, revealing that emissions and CO\({}_{2}\) concentrations dropped sharply when the engine ceased running. This synchronisation of the WLTC test data is critical for accurately calculating the vehicle's energy performance and emissions. The distance travelled by the vehicle during the WLTC cycle was calculated by accounting for the vehicle's speed recorded at one-second intervals \(v_{vob_{n}}\) (km/h):  
\[S_{vob_{n}\_{NLTC}}=\sum_{n=1800}^{1}v_{vob_{n}\_{n}}/3600,\text{km}. \tag{1}\]  
Using the fuel mass gauge data \(B_{f_{m_{n}}}\) (kg/h), recorded at one-second intervals, the fuel mass consumption for each WLTC cycle was calculated:  
\[B_{f_{m}\_{NLTC}}=\sum_{n=1800}^{1}B_{f_{m_{n}}}/3600,\text{ kg}. \tag{2}\]  
The work of the ICE during the WLTC cycle was calculated by considering the engine's brake power recorded at one-second intervals \(P_{B_{B}}\) (kW):  
\[W_{ICE\_{NLTC}}=\sum_{n=1800}^{1}P_{B_{B}}/3600,\text{kW\text{-}h}. \tag{3}\]  
The brake-specific fuel consumption per cycle was calculated based on the fuel mass consumed and the work performed during the WLTC cycle:  
\[BSFC_{WLTC}=\frac{B_{f_{m}\_{NLTC}\cdot 1000}}{W_{ICE\_{NLTC}}},\text{g}/ \text{kW\text{-}h}. \tag{4}\]  
The ICE brake thermal efficiency per driving cycle for various fuels was calculated by evaluating the brake-specific fuel consumption and the lower heating value (LHV) of the fuel, (MJ/kg):  
\[BTE_{WLTC}=\frac{3600}{BSFC_{WLTC}\cdot LHV}. \tag{5}\]  
The mass emissions (g) per unit time (s) of individual compounds emitted by the engine were calculated to provide an objective assessment of emissions. This calculation was based on the pollutant concentrations measured by the exhaust gas analyser, the physical properties of the individual compounds, and data from the ECU regarding fuel and air consumption.