The advantages of cast aluminum auto parts over steel parts. In recent decades, aluminum and aluminum die casting is used more and more in car manufacturing. Aluminum has started to replace steel as base metal for car frames and other parts. Aluminum is said to be stronger and less likely to be corroded than steel. Aluminum alloys are also easier to form, that is why cast aluminum auto parts require less labor costs. However, while labor cost is low, aluminum as a material is also expensive. It is in fact five times more expensive than steel.