The multifuel, stratified charge engine program launched by United Parcel Service in 1978 has progressed through two years of field tests.The mechanical and electronic experience with the field test engine is covered in detail, with problems and causes identified and solutions described.Also included are reports on research initiated as a consequence of problems that appeared in the field test engines.All aspects of engine performance are covered, including fuel economy, multifuel experience, emissions testing and tuning, maintenance expectations and driver reactions.The original 350-engine field test was run with many components newly designed or modified, and relatively untested. Component and reliability problems identified in the field test have prompted modifications, and the engines are being reworked for the start of a new 200-engine field test.Research studies conducted on the field test engine have produced very encouraging emissions data, which suggests that the low-load hydrocarbon problem historically associated with this technology is not a barrier to commercial application. The engine appears capable of passing the heavy duty gasoline engine transient test.And throughout all of the field tests the engine has maintained its exceptional reputation as a fuel efficient power plant, it has consistently produced fuel economy improvements of 30 to 35 percent when compared with the unmodified version of this 292-cubic-inch engine.The engine also has confirmed beyond all doubt its capacity to burn all petroleum distillates between the range of gasoline and diesel fuel, as well as alcohol.A broad range of research and government reports identify this engine technology as among the most promising of alternatives to existing power plants.Rapid progress in refining this technology, however, will not ensure that the considerable benefits of this type of engine are made available to users. A radically different environment exists today than was present in the fuel-short era when this project was started.Eventual employment of this technology to its full advantage appears to depend upon government policy, which now recognizes only engines that burn gasoline or diesel fuel. There are no emissions tests for an engine that can, for instance, run on natural gas pipeline condensate.