Fuel consumption and exhaust emissions of urban buses: Performance of the new diesel technology

Nils-Olof Nylund, Kimmo Erkkilä, Tuukka Hartikka

    Research output: Book/ReportReport

    6 Citations (Scopus)


    The research was carried out by the Finnish Public Transport Association. Altogether seven vehicles were measured, two two-axle Euro 3 -class vehicles as references, three new two-axle Euro 4 -class vehicles and two new three-axle vehicles. The measurements were carried out on a chassis dynamometer, using three cycles describing actual driving. In addition to fuel consumption, exhaust emissions were also recorded for these vehicles. The differences in fuel consumption and operating expenses were after all smaller than first anticipated. In the case of the Euro 3 -class reference vehicles, the difference between the two vehicles was as high as 7-10%. For new two-axle vehicles the difference in fuel consumption, when simulating urban driving, is only 3-4%. Due to different technical solutions, the results were anticipated to be greater. In suburban driving although, the difference is at its most 11%. In the class of two-axle vehicles, lowest fuel consumption was measured for a SCR vehicle, whereas in the case of the two three-axle vehicles, EGR technology resulted in lowest fuel consumption. The measurements do not give an unambiguous answer to whether the EGR- or SCR-technology is preferable regarding fuel consumption. The contemplation is hindered by two factors. On one hand, the order of superiority depends on the driving cycle, on the other, the actual exhaust emissions do not match with expectations. The two EGR vehicles (same make) produced higher NOx -emissions than the manufacturer's Euro 3 -engine. The most fuel efficient SCR -engine is not truly Euro 4 -class what comes to NOx -emissions. Only two of the new vehicles, both with SCR technology, produce NOx -emissions genuinely matching their classes. Both fuel consumption and exhaust emissions have been observed in the study. In case exhaust emissions were completely disregarded, fleet decisions might be directed towards fuel efficient vehicles which after all do not reach the level of emission performance that reasonably could be expected.
    Original languageEnglish
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Number of pages54
    ISBN (Electronic)978-951-38-6923-6
    ISBN (Print)978-951-38-6922-9
    Publication statusPublished - 2007
    MoE publication typeNot Eligible

    Publication series

    SeriesVTT Tiedotteita - Meddelanden - Research Notes


    • public transport
    • urban transport
    • vehicles
    • buses
    • diesel engines
    • fuel consumption
    • exhaust emissions
    • performance
    • measurements
    • operating expences


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