## 4 Results and Discussion
### Level 1: Descriptive Statistics

Table 7: CO\({}_{2}\) emissions (g/km) and total fuel consumption (L/100 km) of each transmission type. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Fuel Type** & **Total Fuel Consumption (L/100 km)** & **CO\({}_{2}\) Emissions (g/km)** \\ \hline D (Diesel) & 9.32 & 250.52 \\ X (Regular gasoline) & 9.98 & 234.05 \\ Z (Premium gasoline) & 11.47 & 268.38 \\ E (Ethanol E85) & 16.62 & 275.43 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: CO\({}_{2}\) emissions (g/km) and total fuel consumption (L/100 km) of each fuel type. From Table 10, it can be seen a similar pattern of gradually increasing from 2017 to 2020 before significantly dropping in the data of engine size, cylinders, fuel consumption in the city, and the total. The highway fuel consumption and in total (mpg) and CO\({}_{2}\) emission observe a continuous rise over the years. That could explain a gradual decrease in CO\({}_{2}\) rating during the period. Finally, smog rating dramatically is reduced in 2018, before continuously growing until 2021. In this research, it is evident that Honda is the greenest brand, and it is essential to analyze its pattern of consumption and emission through the years. From Figure 6, in 2018, Honda seems to have optimized fuel consumption and carbon dioxide emissions of their products. Although the data in 2019 and 2020 show a slight increase, it dramatically drops again in 2021. Given the same analysis on the brand that has demonstrated to possess the least environmental awareness, Bugatti has never considered optimizing their products' consumption and emission, proven by the significant growth in total fuel consumption and CO\({}_{2}\) emission shown in Figure 7.  
Considering the fuel consumption of each fuel type during the years, it can be seen from Figure 8 that Fuel Type E (Ethanol E85) and Z (Premium gasoline) always consume \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Model (Year)** & **2017** & **2018** & **2019** & **2020** & **2021** \\ \hline Engine Size (L) & 3.11 & 3.11 & 3.10 & 3.16 & 3.12 \\ Cylinders & 5.54 & 5.60 & 5.59 & 5.67 & 5.60 \\ Fuel Consumption in City (L/100 km) & 12.42 & 12.36 & 12.37 & 12.38 & 12.27 \\ Fuel Consumption in Highway (L/100 km) & 8.98 & 8.99 & 9.03 & 9.10 & 9.10 \\ Total Fuel Consumption (L/100 km) & 10.87 & 10.85 & 10.86 & 10.90 & 10.84 \\ Total Fuel Consumption (mpg) & 27.67 & 27.65 & 27.66 & 27.63 & 27.86 \\ CO\({}_{2}\) Emissions (g/km) & 250.02 & 250.04 & 251.17 & 253.10 & 253.48 \\ CO\({}_{2}\) Rating & 4.83 & 4.57 & 4.56 & 4.53 & 4.48 \\ Smog Rating & 6.04 & 3.78 & 4.14 & 4.52 & 4.72 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Average feature data over time. Figure 6: CO\({}_{2}\) emissions (g/km) and total fuel consumption (L/100 km) of Honda over time. Figure 7: CO\({}_{2}\) emissions (g/km) and total fuel consumption (L/100 km) of Bugatti over time. more than Fuel Type X (Regular gasoline) and D (Diesel). Over the period, Fuel Type D (Diesel), E (Ethanol E85), and Z (Premium gasoline) all have increased their consumption, whereas Fuel Type X (Regular gasoline) has a slight decrease, thus having the least fuel usage in 2021.