The chart illustrates the emissions of nitrogen oxides (NOx) in grams per kilometer across four distinct vehicle types – diesel cars, gasoline cars, trucks, and buses – at varying speeds ranging from 0 to 130 km/h.
A careful examination of the data reveals notable disparities in nitrogen oxide emissions between the vehicle categories, with variations in emission patterns corresponding to changes in speed.
Initially, buses exhibit the highest emissions, commencing at approximately 40 g/km. This figure decreases slightly to around 37 g/km at a speed of 50 km/h before rising again to nearly 45 g/km at 130 km/h. In contrast, diesel cars start with emissions of about 10 g/km, demonstrating a minor fluctuation before concluding under 8 g/km at the upper speed limit. This trend signifies that diesel cars are consistently the least polluting among the four types across the entire speed range.
Trucks initiate their emissions at about 32.5 g/km, decreasing steadily to 16 g/km at 90 km/h, then experiencing a significant upsurge to nearly 25 g/km by 130 km/h. Buses present a somewhat similar trajectory, beginning near 41 g/km, dropping to 25 g/km at 60 km/h, then significantly increase to 50 g/km at the highest speed. This highlights a particularly noteworthy pattern where both trucks and buses display a similar fluctuation in emissions as speed increases, diverging from the trends observed in diesel and gasoline vehicles.