ABSTRACT
Reduced fuel consumption by lower speeds on roads would reduce emissions. Do drivers, who choose vehicle speed, realize the gain in fuel of a reduced speed? Judgments of fuel consumption at increasing and decreasing speeds were made by professional truck drivers and student groups when they were not driving. For decreases in speed, truck drivers underestimated fuel saved significantly. Engineering and psychology university students’ judgments also tended to underestimate fuel saved but not statistically different from the correct values. For increases in speed, the truck drivers judged the fuel they would waste close to correctly. The psychology student group overestimated the fuel wasted following an increase in driving speed as did the engineering students but only for speed increases greater than 30 km/h. The results indicate that eco driving systems need to support drivers’ judgments of fuel saved or lost if they change their driving speed.
