Why is aluminum being used more in vehicle production?

Aluminum is light weight which helps with fuel economy.

It's lightweight, very strong, and helps lighten a vehicle to improve fuel usage. Parts are easier to replace than steel as most are all bolt on now instead of spot welded in place. Aluminum also is very crash resistant and folds up in the right points and protects the driver and passengers better. Soon, all cars will be aluminum and composite materials. The days of big steel and fiber glass composites are almost gone. Many car companies around the world have been building cars like this for many years now.