* Emissions: The amount of pollutants (like NOx, CO, or hydrocarbons) in exhaust gases. This would vary greatly depending on the engine's condition, the type of fuel used, and whether emission controls are functioning correctly. You'd need to specify *which* pollutant you're interested in and under what conditions (idle, acceleration, etc.).
* Fluid contaminants: The concentration of impurities in engine oil, coolant, or other fluids. Again, this would depend heavily on the condition of the vehicle and its maintenance history.
To get a PPM value, you'd need to specify what substance you're measuring and the method of measurement.