Energy demand assessment for long term operation of hybrid electric vehicles

Abstract

This publication deals with the assessment of fuel demand for long-term operation of hybrid vehicles, because only with this kind of analysis it could be possible to clearly and unequivocally assess the actual progress in achieving the intended goals. The long-term test is the opposite of short-term tests - currently WLTP and RDE or other tests developed mostly by specialized magazines. Long-term car use means mileage measured in thousands of kilometers over a period of several years. The assessment of fuel consumption during long-term operation of HEVs from the presented point of view is new, in which the theory of demand for cumulated energy (as fuel) proved to be very useful. Mathematical models of fuel consumption along with an assessment of its intensity and a description of fuel economy constitute the vehicle’s “energy footprint”. Cumulative fuel consumption increases as mileage increases, but the increase is not a linear function. The discrepancy between fuel consumption in a group of vehicles of the same make and type is significant and increases as mileage increases. The average fuel consumption of the analyzed HEVs during their long-term operation significantly exceeds what is determined by the short tests, e.g. WLTP (and earlier NEDC). The actual fuel consumption is much higher than the one from the short tests.