A Comparison of the Fuel Economy Estimates of a Drive Cycle Developed Using the Road Load Energy Criterion and the Actual On – Road Fuel Economy

Abstract

This study presents a comparison of the fuel economy between a drive cycle developed using the road load energy as an assessment parameter and the actual on road fuel consumption of a common rail direct injection (CRDI) passenger van. Second by second velocity as well as fuel consumption were recorded as the test vehicle traverses a 33 - kilometer pre - determined route in Quezon city, Philippines. The data were processed to generate a drive cycle using the modified Markov Chain approach. A user defined compression ratio was used to determine the length of the generated drive cycle. It was then tested on a chassis dynamometer to measure the fuel economy of the drive cycle. The road load energy, fuel economy, average speed, maximum acceleration and percent idle time were used as assessment variables to determine the quality of the drive cycles developed. Three drive cycles using different compression ratios were generated and yielded the following results: A 676 second cycle which has a 2.22% road load energy error and a 4.9% difference in fuel consumption, the 801 second cycle yielded a 3.06% energy error and 2.8% fuel consumption difference and a 901 second cycle with a 1.34% energy error and a 1.2% difference in fuel consumption. The results suggest that the road load energy criterion is a parameter that can be used to generate drive cycles that will give good on – road fuel economy estimation.