The Jetta TDI has a 2.0-liter four-cylinder turbodiesel engine that operates efficiently enough not to require the new urea-injection technology that many larger, heavier diesels do in order to comply with exhaust emissions standards.
To make dies capable of pressing tiny, intricate patterns onto the threads, LeVey had to borrow a technology often used to create injection molds for detailed plastic parts.
Liquidmetal's injection molding process is still a relatively new technology, and it's fairly expensive -- but that's not necessarily anything that Apple would shy away from.