While magnesium alloys were quite widely used in transport applications in the period from the end of World War
II
until the mid‐1950s, their automotive use then declined virtually to zero. Despite the fact that magnesium is the lightest structural metal and major efforts were made to reduce vehicle mass after the fuel crises of the mid‐1970s, the magnesium content remained well under 1% of the mass of a typical car. However, in the last decade, or so, there has been a huge growth in interest in the possibility of far greater use of magnesium in automobile construction, particularly in the form of high pressure die castings. This has been accompanied by dramatic increase in the volume of magnesium produced and changes in the location of magnesium extraction so that some 85% is now produced in China. The development efforts to produce sheet material more economically via twin‐roll casting, develop superior casting alloys, and achieve a better understanding of their service properties are summarized as are the economic and environmental implications. It is concluded that there are few remaining technical obstacles to greater use but economic and environmental issues remain.