The objective of this study was to develop a predictive eco-cruise control (ECC) system capable of improving vehicle performance and reducing fuel consumption and emissions in areas with steep terrain. Researchers combined a fuel consumption model with a powertrain model to create a predictive ECC system for light vehicles. System performance was evaluated on a 28-mile section of Interstate-81 in Virginia where six test vehicles equipped with conventional cruise control (CC) systems were used to calibrate the model and determine fuel consumption rates with and without ECC on a variety of roadway grades that ranged from +4 percent to -4 percent.
The system concept enabled drivers to pre-set target cruise speeds and system parameters. Using topography information from onboard navigational devices the ECC system was designed to automatically update plans for throttle, braking, and gear selection to optimize fuel efficiency when approaching roadway grade changes.
Researchers compared fuel economy, throttle control, and travel time differences between ECC and CC for multiple scenarios and then extrapolated the findings to a national level to estimate impacts if all light vehicles could be equipped. The national estimate was calculated by applying national VMT transportation data to the differences in fuel consumption rates determined from simulation.
- The I-81 simulation found that real-time applications for predictive ECC can reduce fuel consumption up to 15 percent when compared to conventional cruise control systems, however, for maximum fuel efficiency without increasing overall travel times proper ECC speed ranges must be selected.
- Initial simulations compared ECC against CC system performance on a route from New York City to Los Angeles (2790 miles) and found that fuel consumption decreased by 12 percent and travel time increased by 7 percent when the ECC system was set to fluctuate between +5 and -5 mi/hr.
- With a revised ECC speed range setting of +5 and -1 mi/hr fuel consumption decreased by 4.7 to 6.7 percent and travel time was similar to that of CC.
- Benefits were projected to a national level by assuming that all light vehicles could be equipped. Potential average fuel savings were estimated at roughly 1.04 billion gallons per year.