This study examined the changes in the U.S. in vehicle fuel economy, distance travelled, and vehicle load (occupants carried) between 1970 and 2010, and the effects of those changes on the amounts of fuel consumed. All light-duty vehicles were included in the analysis.
The results indicate that during the 40-year period examined, vehicle distance travelled increased by 155%. However, because vehicle load decreased by 27%, occupant distance travelled increased by only 57%. Vehicle fuel economy (of the entire fleet of light-duty vehicles) improved by 40%. However, because of the decrease in vehicle load, occupant fuel economy improved by only 17%. As a consequence of the changes in vehicle fuel economy, vehicle distance travelled, and vehicle load, the total amount of fuel used increased by 53%.
Also included in the report is a brief discussion of the effects of potential future changes in vehicle fuel economy, vehicle distance travelled, and vehicle load on the amount of fuel used. Considerations included were increased vehicle distance travelled as a consequence of improved vehicle fuel economy, and decreased vehicle distance travelled and worsened vehicle fuel economy as consequences of increased vehicle load.