"Engine friction" refers to the resistance or rubbing force that occurs between moving parts within an engine. It is the energy lost or wasted when these parts interact, which can affect the engine's efficiency and performance. Full definition
The resulting rapid engine warming improves heating in the car's interior and reduces engine friction during the warm - up process. (greencarcongress.com)
My leading theory is both key switch and starter or excessive engine friction. (mechanics.stackexchange.com)
The company says that the reduction in engine friction has led to CO2 emissions coming down to 42 g / km from 44 g / km. (indianautosblog.com)