The humble rivet.
That's what Demos Hoursoglou, Jaguar Land Rover's body-in-white manufacturing manager here, puts near the top of his list of worries about assembling the aluminum body of the Range Rover.
The 2014 Range Rover body uses 17 types of rivets, 3,722 per vehicle. If one jams in a gun or is inserted incorrectly, production stops.
Before a rivet reaches the production line, it is inspected at least twice, sorted and X-rayed. Each shipment of bar-coded rivets must be matched to the exact guns that will shoot them into the aluminum body parts.
Source
Automotive News