This report covers the first 3 months effort of the Ford/DOE Automotive Stirling Engine Development Program, specifically Task I which is Fuel Economy Assessment. At the beginning of this contract effort the projected fuel economy of the 4-215 Stirling engine was 21.16 MPG with a confidence level of 29 percent. Since that date, the fuel economy improvement projection of the 4-215 Stirling engine has been increased to 22.11 MPG, with a confidence level of 29 percent. Collection of fuel economy improvement data is directly related to engine durability. Engine durability has been limited. Since September 19, 1977 a total of 47.7 hours of engine running time has been accumulated using two engine builds. Progress is reported in sub-task studies of burners, preheaters, engine drive, blower system, power control, air-fuel ratio control, cooling system, and cycle control. (LCL).