45 percent each, Novelis predicts. That's despite expectations that Asia will continue to account for over half of global vehicle output, according to IHS Automotive.
"This substitution from steel is being driven mainly by strict emissions regulations, especially in North America, and is a game changer for the aluminium rolling sector," said Charlie Durant, senior consultant at CRU, a metals consultancy. "In Asia, the emissions regulations are less stringent and vehicles tend to be much smaller."
"The relative cost of aluminium sheet is seen as a prohibitive factor, so it's in regions with the most stringent legislation ... that this material will be most widely adopted,".
European luxury brands such as Volkswagen AG's Audi and BMW AG are expanding their use of aluminium in high-end, high-margin cars. Ford will begin building its flagship F-150 pickup with an aluminium body later this year, making it the first such mass-market vehicle.
Hyundai, Toyota Motor Corp and other Asian automakers, however, mostly produce mass-market cars on highly efficient assembly lines that are often decades old. They don't sell luxury cars in high volumes and can't demand the sorts of prices that Audi and BMW can.
Aluminium can cost some four times more than steel, although aluminium is up to 30 percent lighter than conventional steel and 15 percent lighter compared to advanced, high-strength steel, according to consultancy Wood Mackenzie. A switch to aluminium increases not only materials costs but requires heavy investment to overhaul production lines.
"If you start making a completely different architecture for Lexus from Toyota or Infiniti from Nissan, you will get into a cost problem because the numbers sold and the premium price they get is not similar to the Germans," Thorstensen said. "All manufacturers in Asia face that same problem. They can't get the premium price so they have to be much more careful."
The previous version of Hyundai's Genesis had an aluminium hood, but the company switched to steel for the current model, launched in late 2013, making it heavier and less fuel efficient than its predecessor, two of the people said.
An aluminium car hood weighs about half of one made of steel, according to Novelis. Every 10 percent reduction in vehicle weight improves fuel economy by 6-8 percent, according to the U.S. Department of Energy.
In 2010, when Hyundai began developing the current-generation Genesis, shaving weight and increasing fuel economy was a concern, said one of those familiar with the matter.