Computer Simulations of Emissions and Fuel Economy

A simulation of the exhaust emission testing system including a vehicle, dynamometer and driver on General Motors' analog-digital hybrid computer is described. The simulation predicts instantaneous and average results for hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NO_x), carbon dioxide (CO₂), and fuel economy over a predefined speed schedule such as the Environmental Protection Agency's (EPA's) city and highway schedules.

The simulation facilitates the study of sensitivity of several parameters which influence emissions and fuel economy. The usefulness of the simulation to study the effect of test parameters, test operating conditions and product changes such as the engine, transmission, axle, etc., on emissions and fuel economy is outlined. Results from some of these sensitivity studies are also presented.