What are the disadvantages of aluminium fir building cars

Disadvantages of aluminum in building cars include:

On average, aluminum is more expensive than steel, as much as two to three times.

Aluminum is not easily welded. If a steel door or panel suffers a crack, often it cam be welded back together easily, primed and repainted so its difficult to tell any body work has been performed. This cannot be done with aluminum. Steel  also can be bent and shaped as needed.

Body shops and even dealer service centers  are currently  equipped for steel work with technicians skilled in the art of welding and steel fabrication. The cost of switching over to an infra structure designed specifically for all-aluminum  vehicles or mass production of aluminum vehicles and components would be high.