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AS a basis for the analyses of this symposium, a hypothetical car has been used to evaluate the engine power distribution in performance. Effects of fuel,-engine accessories, and certain car accessories are evaluated. The role of the transmission in making engine power useful at normal car speeds is also discussed. Variables encountered in wind and rolling resistance determinations are reevaluated by improved test techniques. Net horsepower of the car in terms of acceleration, passing ability and grade capability are also summarized.

Magnesium alloy extrusions offer potentially more mass saving compared to magnesium castings. One of the tasks in the United States Automotive Materials Partnership (USAMP) ?Magnesium Front End Research and Development? (MFERD) project is to evaluate magnesium extrusion alloys AM30, AZ31 and AZ61 for automotive body applications. Solid and hollow sections were made by lowcost direct extrusion process. Mechanical properties in tension and compression were tested in extrusion, transverse and 45 degree directions. The tensile properties of the extrusion alloys in the extrusion direction are generally higher than those of conventional die cast alloys. However, significant tension-compression asymmetry and plastic anisotropy need to be understood and captured in the component design.

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 (NOx), 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.