Technology is not now a primary limiting factor in the fuel economy achieved by the U.S. new-car fleet, nor is it likely to be in the near future. Technology is a limiting factor to the extent that it determines the fuel economy that can be achieved in cars of a given size.While means are generally available to achieve significant improvements in the fuel economy of cars of all sizes -- by making them lighter in weight for given interior dimensions, refining powertrains, and making other design improvements -- costs can be rather high, and benefits in the marketplace uncertain. Sophisticated design approaches are needed not for fuel economy alone but also to continue providing amenities such as ample interior space and carrying capacity, luxurious and quiet surroundings (which unavoidably add weight), higher performance levels, air conditioning and power accessories -- while also improving gas mileage.Based on such considerations, the Office of Technology Assessment has projected average new-car fuel economies through the end of the century according to two scenarios*. The low scenario, relatively conservative technically but assuming continuing market demand for better fuel economy, results in the following estimates for the average gas mileage of new cars sold in the United States, based on EPA 55 percent city/45 percent highway ratings. The high scenario, with a major shift toward smaller cars, points to an average new car gas mileage rating greater than 70 mpg by 2000.OTA's projections show that continued improvement in automobile fuel economy beyond a 30 mpg baseline new-car average in 1985 could save 0.6 to 1.3 million barrels of oil per day by 2000, depending on the size mix of future new car sales and the technologies these vehicles embody.