The current extensive revisitation of the application of gasoline direct-injection to automotive, four-stroke, spark-ignition engines has been prompted by the availability of technological capabilities that did not exist in the late 1970s, and that can now be utilized in the engine development process. The availability of new engine hardware that permits an enhanced level of computer control and dynamic optimization has alleviated many of the system limitations that were encountered in the time period from 1976 to 1984, when the capabilities of direct-injection, stratified-charge, spark-ignition engines were thoroughly researched. This paper incorporates a critical review of the current worldwide research and development activities in the gasoline direct-injection field, and provides insight into new areas of technology that are being applied to the development of both production and prototype engines.The advantages and disadvantages of the emerging technologies that are being utilized to develop gasoline direct-injection combustion systems, such as electronic common-rail injection, variable swirl and tumble control, computational fluid dynamics, and laser diagnostics of fuel sprays and combustion are discussed in detail within the context of the total industry effort to enhance the attainable brake specific fuel consumption and emissions. Significant emphasis is placed upon extracting the key findings of each investigation and discussing the relative potential of the technique for meeting the major requirements of the gasoline direct-injection engine. Areas of general consensus that are evident among the hundreds of researchers who are currently investigating this field are noted, as are apparent conflicts that must be resolved in the near future by obtaining additional data. Also noted and discussed are a number of critical research areas for which it is obvious that insufficient effort and resources are being devoted. One example of such an area is the development of a proven laboratory test for quantifying the deposit formation tendencies of direct-injection gasoline injectors.Based upon the review of all available technical publications, the trends and directions of the current effort on gasoline direct-injection engine are noted, and the remaining difficult developmental areas are discussed. For planning purposes, the totality of the literature is used to formulate likely engine scenarios regarding the development of specific engine configurations, and to outline technological path options and trends that may be expected in the displacement of the port fuel injection engine by the gasoline direct-injection engine.