Fuel Consumption of Backward Vehicle Simulation Following Minimum Fuel Consumption Curve for Optimum Gear Ratios

Fuel consumption is a critical concern for both environmental and economic reasons. This study proposes a method to operate an engine near the minimum fuel consumption curve by adjusting gear ratios. Using a one-dimensional backward vehicle simulation model, the actual fuel consumption is controlled to follow the desired fuel consumption derived from the Honda Insight fuel conversion map through a proportional–integral–derivative-based approach. Actual fuel consumption, which comes from the driving cycle, and desired consumption, which comes from minimum fuel consumption, are used to determine the optimal gear ratio by supposing that the manual transmission Honda becomes a continuous variable transmission and that gear ratio is a control input for tracking between actual and desired fuel consumption. The minimum fuel consumption curve is obtained from the intersection of constant power and fuel mass flow rate curves. The accuracy of tracking between desired and actual fuel consumption is evaluated across standard driving cycles (New European Driving Cycle, worldwide harmonized light vehicle test procedure Class-3, highway fuel economy test driving, federal test procedure), yielding R2 values of 0.94, 0.91, 0.88, and 0.91, respectively. These results demonstrate that variable gear ratios can enable operation close to the minimum fuel consumption curve under real driving conditions by considering gearbox dimension limits.