New Directions: A heavy burden for heavy vehicles: Increasing vehicle weight and air pollution

摘要

The relationship between vehicle weight and fuel use is well-established. It is estimated that, as a rule of thumb, a 10% decrease in vehicle weight leads to a 5-7% decrease in fuel consumption (World Business Council for Sustainable Development (WBCSD), 2004, Mobility 2030: Meeting the challenge to sustainability). For this reason, reductions in vehicle weight could result in large reductions in fuel use and hence CO_2 emissions. But vehicle weights have not been decreasing in recent years—they have been increasing. In Europe, passenger car vehicle weights have increased by 30% in the last 30 years (WBCSD, 2004, Mobility 2030: Meeting the challenge to sustainability). Similarly, the US EPA calculates than in the US there has been a 25% increase in light-duty vehicle weights from 1985 to 2005 (Heavenrich, 2005, Light-duty automotive technology and fuel economy trends: 1975 to 2005, Executive Summary, United States Environmental Protection Agency, Report no. EPA420-S-05-001). Furthermore, Fig. 1 shows that in the US, vehicles weigh around 50% more than their European counterparts. The US EPA estimates that had the 2005 light-duty vehicle fleet had the same distribution of performance and weight as in 1987, it could have achieved about 24% higher fuel economy, highlighting the clear benefit of reducing vehicle weight on CO_2 emissions. These increases in weight are driven by many factors such as improved safety requirements, higher specification vehicles and a growing demand for larger vehicles such as sports utility vehicles.