This is an assessment of current two-stroke automotive engine technology, implementation policy, vision, goals, and engine development and commercialization strategy. It includes a historical review of key two-stroke Otto cycle engine developments, a summary of the specifications for the new: Suburu Super 2-stroke, Toyota S-2 gasoline engine, Orbital two-stroke, General Motors GMCDS2 two-stroke engine and Industrial Technology Research Institute (ITRI) two-stroke engine test technology in Taiwan.Although two-stroke engine technology has been under development since the end of the 19th century, currently the only mass produced vehicles powered by two-stroke cycle engines are the Trabant and Wartburg, with 594 cc two cylinder and 993 cc three cylinder engines, respectively, essentially unchanged in cylinder configuration and porting since 1931. VEB Sachsenring Automobilwerke Zwickau-Trabant and VEB Automobilwerke Eisenach-Wartburg are the manufacturing plants in East Germany, (GDR) (1)(2)(3)(4)1Annual production peaked in 1987 at about 218,000 cars per year, but declined to 146,000 Trabant two-stroke vehicles by 1989, when, in the Autumn of 1988, the Wartburg switched to the four-stroke 1.3L4 VW engine. Furthermore, Trabant will switch to the four-stroke 1.0L4 VW Polo and two-stroke engine production essentially ended September 1990, because the Trabant/Wartburg two-stroke engines do not meet the vehicle performance and exhaust emission standards of West Germany (FRG), (5)(6)(7)(8)(9)(10).On the other hand, in Austria, France, the United Kingdom, Australia, Japan, Taiwan and the United States, interest in the development of two-stroke automotive spark ignition engines has increased significantly. Because of this revival of activity in America and the Orient, coupled with the switch from two-stroke to four-stroke cycle gasoline engine production in the (GDR), this assessment was undertaken to determine the prospects for two-stroke mass production in the Western and Oriental nations.