Auto manufacturers have increased speed and productivity through the use of rapid prototyping. It's a process that typically involves designing a potential new vehicle part with special computer software and using those specs to create a physical model with a machine such as a 3-D printer.
If you're unfamiliar with the process of building a prototype, the inherent benefits of this technique might not be readily apparent, but it is a huge timesaver compared to more archaic methods. Instead of taking weeks to design and construct a prospective part, it takes just hours or days. That means product testing is similarly sped up and designers can tell if they have a dud without wasting tons of time and money. Design flaws are indentified quickly and, probably most important, before they hit the production line.
This technology was assimilated rapidly into auto manufacturing because as anyone who's ever looked under the hood of a vehicle knows for certain: Cars contain an awful lot of parts.