And what are the advantages/disadvantages of steel aluminum in building cars?Which would be better for building cars?Steel and aluminum are both pretty strong, but aluminum is lighter. This gives a better strength/weight ratio. Aluminum is not as easy to weld as steel so this is a disadvantage but it is easier to sheet-form and do simple machining on. Aluminum would be better than steel for cars as it is strong enough while being much lighter - ending up in a faster, but equally dangerous hot rod.Similarities - They are both metals, conduct electricity and heat and deform elastically then plastically. Difference - every mechanical property there is! Density, elastic modulus (stiffness), strength and hardness are all higher for steel. But, for building cars it is about design, weight, forming, manufacturing, joining and cost. Better depends on what you are trying to acheive - cost or weight saving - and there is not a hard and fast rule as to which metal helps which. Have a look at either the Jaguar S type which is aluminium (as is the Audi A6). Most Ford cars are still steel (as are Renault). Check out the crash test results.Erm im no expert, bt I dont think aluminum is very strong, thus not very safe for a car!Other related question