Rising fuel costs as well as mandated greenhouse gas reductions have led commercial vehicle manufacturers and operators to focus on improving fuel economy.Fuel costs are a large part of their fleet operating expenses.Efficient engine lubricants can play a role in reducing fuel consumption and can be evaluated in well-established tests such as the ASTM D7589 Sequence ⅥD engine dynamometer test procedure.However,achievements resulting in lower fuel consumption can also be obtained through improvements in drivetrain systems,in terms of both hardware and lubricants.Although there are no published industry standards for testing the fuel economy benefits of transmission or axle lubricants,driveline component tests can be used to evaluate efficiency on a subsystem scale.This paper describes current procedures used to measure fuel economy through various tests and on-road evaluations.