Improved fuel economy is a key measure of performance in the automotive industry,
driven both by market demand and increasingly stringent government emissions
regulations. In this climate, targeting even small benefits to fuel consumption
(FC) can have a large impact when considering fleet average CO2
emissions. Lubricant properties over the course of an oil drain interval (ODI)
directly influence long-term fuel consumption. Furthermore, viscosity control
gasoline additives have been shown to provide FC benefit via fuel-to-lubricant
transfer. This study investigated whether consistently fueling with gasoline
containing friction modifier (FM) additives could provide a long-term fuel
consumption benefit via a lubricant transfer mechanism.
A robust fleet trial method was employed to quantify fuel consumption benefits of
two friction modifier additive packages relative to a baseline deposit control
additive (DCA) package in a 95 RON, E5 fuel. FC was measured for 32 market
relevant vehicles over the course of a European ODI. The test was performed with
12,000 mile on-road accumulation in a 60/40 urban/high speed driving route.
Changes in FC were measured periodically on a chassis dynamometer (CD) using the
industry standard New European Drive Cycle (NEDC) procedure. NEDC emissions
results demonstrated statistically significant FC benefits for fuels containing
FM additives relative to a DCA only reference fuel, with 0.60% and 0.71% benefit
at the 95% confidence level. Lubricant analysis confirmed transfer of FM
additives to the lubricant sump, providing support for a fuel-lubricant
interaction mechanism. This study thus demonstrates that statistically
significant long-term fuel consumption benefits can be obtained by consistent
fueling with FM dosed gasoline.