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The fuel economy data compiled by the U.S. Environmental Protection Agency (EPA) have been analyzed to determine the trends in passenger car fuel economy beginning with model year 1957. This paper adds the 1976 model year data to the historical trend and concentrates on comparisons between the 1976 and 1975 models. Calculation procedures which allow the changes in fuel economy to be determined separately for system optimization, new engine/vehicle combinations, and model mix shifts have been employed in the analysis which compares 1976 models with 1975 models. A wide range of percentage changes was seen for the fifteen manufacturers who were certified in time to be included in the analysis performed for this paper. The net change in fuel economy for the 1976 new car fleet has been estimated at +12.8% compared to the 1975 new car fleet. System optimization is responsible for 8.8% of the improvement and model mix shifts are projected to account for +3.1% of the change.

The fuel economy data obtained from the emission tests run by the U.S. Environmental Protection Agency (EPA) have been used to show passenger car fuel economy trends from model year 1957 to present. This paper adds the 1975 model year to the historical trend and concentrates on comparisons between the 1975 and 1974 models. Methodologies which allow different 1975 vs 1974 comparisons to be made have been developed. These calculation procedures allow the changes in fuel economy to be determined separately for emission control systems, new engine-vehicle combinations and model mix shifts. Comparisons have been calculated not only for the fleet as a whole but for each of the 13 manufacturers who were certified as of the time this paper was prepared. The net change in fuel economy for the fleet has been estimated at +13.8% comparing the 1975 models to the 1974 models assuming no model mix change occurs.

Several sets of repetitive test data using the 1975 Federal Test Procedure ('75 FTP) have been analyzed to establish the variability of each component measured during each phase of the test. The variability characteristics of four different emission control systems have been discussed and compared. The overall variabilities of the '75 FTP composite values have been assessed at ±6% for hydrocarbons and CO, ±3% for NOx, and ±1% for CO2. The extremely repeatable behavior of the CO2 emissions is utilized to calculate the fuel economy during the test. This calculation is discussed and some fuel economy results from repetitive tests are presented.

This paper reports the results of an exhaust emissions characterization from the non-catalyst control systems employed on the Mazda RX-4 rotary, the Honda CVCC, and the Chrysler electronic lean burn. Throughout the paper, exhaust emissions from these vehicles are compared to those from a Chrysler equipped with an oxidation catalyst and an air pump. The emissions characterized are carbon monoxide, hydrocarbons, nitrogen oxides, sulfur dioxide, sulfates, hydrogen sulfide, carbonyl sulfide, hydrogen cyanide, aldehydes, particulate matter, and detailed hydrocarbons. A brief description of the sampling and analysis procedures used is included within the discussion.