Engines, systems, devices, software, and methods of the present invention provide increased fuel efficiency and emission performance. The engine may include a magnesium alloy cast engine block cast as a mono-block with or without a ceramic inner core and including one or more cylinders designed to provide compression ratio of 10:1 to 14:1. Each cylinder may include one or more laser igniters, one or more supercritical fuel injectors configured to inject the fuel near or in a supercritical state, and carbon dioxide, which may be in the form of engine exhaust gas. The fuel may be diesel, gasoline, or other suitable hydrocarbons that may be cracked into smaller molecules prior to be injected into the cylinder.

A cellular structure may include a plurality of cells. Each cell of the plurality of cells may have a twelve-cornered cross section. The twelve-cornered cross-section may include eight sides each having a first cross-sectional length, and four sides each having a second cross-sectional length that differs from the first cross-sectional length.

The present invention relates to an aluminum alloy having low density and enhanced heat resistance. An aluminum alloy having improved high temperature physical properties comprises: magnesium (Mg) in an amount of about 7 to about 11 wt %, silicon (Si) in an amount of about 4 to about 8 wt %, copper (Cu) in an amount of about 0.5 to about 2 wt % and manganese (Mn) in an amount of about 0.3 to about 0.7 wt %, and a balance of aluminum based on the total weight of the aluminum alloy. Vehicle parts such as a piston, a housing and/or a bed plate of high power engine, to which the aluminum alloy may be applied, are provided as well.