Effects of altitude on On-Board Fuel Consumption and CO₂ Emissions of a Vehicle: An analysis based on experimental data

Abstract

Fuel efficiency and CO₂ emissions of vehicles are influenced by various factors, including altitude, whose effect is often ignored or underestimated. This study evaluates the effect of altitude on fuel consumption and CO₂ emissions in a light vehicle through an experimental campaign in four cities in Ecuador located between sea level and 3,000 meters above sea level. Fuel consumption and engine operation data were obtained through the OBD system. This information was used to generate engine maps and analyse vehicle performance at different altitude levels.The results showed that in cities at higher altitudes, the vehicle operated with engine loads above 70% due to slopes greater than 7%, while in coastal cities the loads were lower. Under similar engine load conditions, both fuel consumption and CO₂ rates were lower in high-altitude cities, showing a positive effect of altitude on combustion. However, energy-based emission factors were higher in high-altitude cities, probably due to lower air density. In terms of distance, fuel consumption and CO₂ emission factors were up to 7% higher in high-altitude cities. Overall, this study proposes a low-cost methodology and shows the importance of considering the effect of altitude when designing sustainable transport strategies for Latin American cities.