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The results reported are from tests on July 6-8, 1999, on a limited-access 12km section of I -15 in San Diego. The tests involved 2, 3 and 4-car platoons operated and maintained by PATH personnel under the auspices of CALTRANS and utilized Buick LeSabre sedans under fully automatic longitudinal and lateral control. Multiple sensor data was acquired, including the fuel injector pulse width. We demonstrate that the fuel injector pulse width, in combination with engine RPM and forward speed, can be used to determine accurate estimates of instantaneous fuel consumption. The repeatability for total fuel consumed over a 2.4 km portion of the test path is ±1% based upon multiple single car runs over the three day period, with the major portion of the uncertainty arising from changing wind conditions. Fuel savings for individual vehicles vary from 0-10% depending upon number of vehicles, vehicle spacing, and vehicle position within the platoon.

This paper presents field test results for fuel savings by means of flat flaps attached to the base of a standard semi trailer. The flaps are constructed from a fiberglass-epoxy-resin material and have a length equal to one-quarter of the trailer-base width (about 61 cm or 2 feet). They are attached along the rear door hinge lines on either side of the trailer and along the trailer roof-line so that no gap appears at the joint between the flap and the trailer base. The flap angle is variable and can be set to 10, 13, 16, 19 or 22 degrees. Tests were conducted in May 2004 at the NASA Crows Landing Flight Facility in the northern San Joaquin Valley, California. Analysis of the data show fuel consumption savings at all flap angle settings tested, when compared to the “no flaps” condition. The most beneficial flap angle appears to be 13 degrees, for which the fuel consumption is 0.3778 ±0.0025 liters/km compared to the “no flaps” control of 0.3941 ± 0.0034 liters/km.