Improvements in vehicle fuel efficiency continue to be a significant driver for all parties involved in the operation of automotive vehicles. The cost of vehicle ownership, energy security and the need to limit greenhouse gas emissions are all factors in driving the need to improve operating efficiency.
One particular area of interest is engine lubricants which are known to have a significant effect on the overall efficiency of a vehicle. The decision to move to a more fuel efficient lubricant is enhanced since the incremental cost of introducing a fuel efficient lubricant is low in comparison to the potential fuel saving leading to a favourable economic decision for a fleet owner.
This paper describes a study undertaken where upon two significantly different UK buses were taken directly from the FirstGroup fleet and used for a period of two weeks for fuel economy testing. The testing centres on two commercially available engine lubricants and was completed on a test track in the UK.
Each bus tested both fluids using a drive cycle derived from data obtained from real bus routes in the UK.
In addition to a large number of test runs, an innovative data analysis and statistical approach was utilised in order to validate all data recorded during the study.
This method enabled the authors to overcome the weaknesses of a highly variably study demonstrating statistically significant fuel consumption savings in two independent urban transit vehicles operating under a real world track based test cycle.