Fuel Consumption of Gasoline Vehicles at High Speeds: Field Evaluation and Estimation Method

The main objectives of this paper are two fold. First, the paper evaluates the impact of vehicle cruise speed on its fuel consumption rates at speeds up to 95 mph using field data gathered under real-world driving condition. Second, it investigates the fuel consumption during acceleration events and proposes a new method to estimate fuel consumption for these conditions. A Portable Emissions Measurement System (PEMS) unit was used to measure tail-pipe emissions of four light-duty gasoline vehicle. The fuel consumption rates were calculated based on standard carbon balance equation. The vehicles were tested on a 9-mile high speed track in Pecos, Texas while driving according to a pre-developed drive patterns. The drive patterns were used to ensure a good coverage of various steady-state and transitional operational modes of the vehicles. The results show the fuel economy of regular gasoline-powered vehicles drops drastically from 40 mph o 70 mph and then will follow a moderately decreasing pattern. A new metric, Fuel Acceleration Rate, was proposed and used to investigate the change in fuel consumption during an acceleration event. It was found that the minimum amount of fuel required to achieve a 1 mph increase in speed follows an exponential functional form. A regression relationship was developed to explain this pattern. Finally, calibration equations were established to estimate coefficients of this equation based on vehicles’ rated power and power-to-weight ratio. The proposed provides an easy to use tool to estimate fuel consumption and emissions inventories in applications such as such as sketch-planning, travel demand modeling, and mesoscopic traffic simulation.