The development work to combine high-strength steel, with aerospace quality adhesives is no small thing. It will devour engineering resources, and the end result will be the result of spending huge amounts of money on time and talent. Car companies don't do all of this just for the good of their customers, but also to prove a point about how serious they are, in terms of global competition.
The details included here mean that these engines are virtually re-invented and changed so dramatically that they represent the closest thing to a brand new design, especially the 2-litre Nu engine. Again, this represents a huge financial investment.
The early Hyundai engines were agricultural at best, and primitive at worst, but you have to start somewhere and the Hyundai Group's technology and quality improvements are strong evidence of a committment to match the world's best, and exceed those standards.
I'm also impressed with the advancement in 'clean and green' technology in the 2017 Elantra, just take the seats for example: