Research Projects

The effect of dynamometer inertia weight and road load horsepower, vehicle tune parameters, and smoothing the emission test driving schedule on exhaust emissions and fuel economy were studied. Actual vehicle road-load horsepower was measured by coast-down time and engine manifold vacuum. Tests were performed on 50 1968 through 1975 model year vehicles. 1975 and Modified 1972 Federal Test Procedures were used.

Observed differences in exhaust emission and fuel economy test results were tested for statistical significance. Vehicle coast-down times showed actual vehicle road load horsepower was, on the average, 42% greater than the horsepower schedule used in the Federal Test Procedure at a very high level of statistical significance.

This report was submitted in fulfillment of Project Number 2110 and Contract Number ARB4-726 by Automotive Environmental Systems, Inc. under the sponsorship of the California Air Resources Board. Work was completed as of December 22, 1975.