A Preliminary Comparison of Fuel Economy Estimates from Driving Cycles Developed Using Road Load Energy-Based and Microtrip Methods

This study presents an experimental comparison of on-road fuel economy estimates of driving cycles generated by a locally-developed road load energy (RLE)-based method developed by Gerald Jo Denoga and the micro-trip approach. A Philippine public utility jeepney (PUJ) plying a selected local franchised route was fitted with on-board instrumentation to gather on-road speed-time data and fuel economy measurements for a total of 18 round-trips. These speed-time data were processed using computer codes written for both methods of generating drive cycles for chassis dynamometer testing. Candidate drive cycles developed by the RLE-based method were selected based on the calculated energy errors and residue errors of developed drive cycles. The candidate drive cycles developed by the micro trip method were selected by the absolute value difference of probability distribution of normalized frequencies. Drive cycles with duration of 540, 720 and 900 seconds developed from the RLE-based method were selected while a 1400-second drive cycle from the micro-trip method was chosen as representative of the on-road driving pattern. Chassis dynamometer testing of the PUJ vehicle was performed using the drive cycles generated by both the RLE-based method and micro-trip method to measure their corresponding fuel economy estimates. The results were then compared with the measured on-road fuel economy. For the on-road tests, an average fuel economy of 7.3 km/liter was obtained. The RLE-based driving cycles gave an average fuel economy of 7.0-7.1 km/liter, energy error of 2.19% - 4.36%, and residue error of 1.33% - 2.03%. The micro-trip-based driving cycle yielded an average fuel economy of 6.8 km/liter and absolute value difference of 9%. The results suggest that driving cycles developed using the RLE-based gave better estimates of actual on-road fuel economy.