Cold filter plugging point (CFPP) is the lowest temperature, expressed in degrees Celsius (°C), at which a given volume of diesel type of fuel still passes through a standardized filtration device in a specified time when cooled under certain conditions.
The test is important in relation to the use of additives that allow spreading the usage of winter diesel at temperatures below the cloud point.
Current additives allow a CFPP of −20 °C to be based on diesel fuel with a cloud point of −7 °C.
One of the real diesel motors however stopped working even before the legal minimum was reached, presumably due to an undersized filter heater.
Notably the experiments did not show a direct correlation between the CFPP value of the mineral oil and the cold start capability of the diesel motors – hence the automobile club suggest the creation of a new test standard.