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.