In comparing the use of cast and wrought aluminum to reduce vehicle weight and energy consumption, cast aluminum is generally regarded as less energy intensive based on the extensive use of secondary aluminum in castings. Cast aluminum also offers potentially larger direct weight savings than wrought aluminum. However, increased use of aluminum in either cast or wrought form will require that the added demand be matched by a corresponding increase in primary aluminum production. Further, virtually all potential casting applications are in chassis parts which will generally yield lesser indirect weight savings than upper body applications of wrought aluminum. Despite these limiting factors, the substitution of cast aluminum for cast iron appears to compare favorably with the replacement of steel by wrought aluminum on the basis of general estimates of energy savings. In particular, the selective use of cast aluminum to reduce the weight of optional engines may offer opportunities to maximize weight and energy saving per unit of substitute material used.