Effects of altitude on light gasoline vehicles: fuel consumption and air pollution

Driven by the global carbon neutrality goal and emission regulations, gasoline vehicles' fuel consumption and emission characteristics in the plateau environment have received extensive attention. In this paper, the running resistance of light gasoline vehicles in a high-altitude environment laboratory is corrected by coasting resistance tests to ensure the accuracy of laboratory tests. Finally, a constant speed fuel consumption test and a New European Driving Cycle emission test were carried out in the high-altitude environment laboratory. The results of fuel consumption characteristics show that at low-to-medium speeds (below 5,000m altitude), fuel efficiency generally improved with increasing altitude. For the high-speed range, air resistance becomes more prominent below 5000m, which reduces overall fuel consumption. However, once the altitude approaches 5000m, all speed ranges show an upward trend in fuel consumption. Fuel consumption at high speeds enters an upward trend earlier (at relatively low altitudes). The results of emission characteristics show that the emission of CO and THC increases significantly with the increase of altitude due to combustion deterioration. The contribution of the cold start-up phase increased significantly (77.1 % CO and 66.3 % THC), which became the core factor of the increase in emissions. Due to the game between the combustion temperature and the efficiency of the three-way catalytic converter (TWC), NOx emission shows a trend of first decreasing and then increasing. Its instantaneous emission characteristics are not stable because of the gradual decline of TWC performance. In general, these results can be used to drive vehicle energy efficiency and emission reduction targets.