Abstract: A process and apparatus are disclosed for estimating evaporative fuel emission losses from a vehicle having a hydrocarbon-fueled engine operating under control of a microprocessor-based powertrain controller, a fuel tank with an evaporated fuel emission control system comprising a fuel vapor adsorbtion means connected to the tank and engine, and a diagnostic system that detects malfunctions in the vapor adsorbtion means. The process and apparatus measures temperature inside the vehicle passenger compartment at successive times when the engine is not running and determines the lowest temperature during partial diurnal and diurnal cooling cycles and uses such temperature along with any malfunction data to estimate evaporated fuel loss during a test period.

Abstract: A method for analyzing automotive vehicle emissions detects and logs significant engine events over a test period, and applies the logged events to a model defining the emissions impact of such events to yield a vehicle emissions estimate for the test period. The method includes a diagnostic for diagnosing a deviation in performance of emissions control systems away from an expected performance and for correcting the vehicle emissions estimated to reflect the operating condition of the emissions control systems.