General Motors turns steel, aluminum, and battery cells into Chevrolet, GMC, Cadillac, and Buick vehicles, but the speed at which it does that is set by paint booths — every body must clear a multi-stage paint process with fixed cure times before a single seat or wire harness can be installed, and those cure times cannot be shortened without triggering defects that require rework. Because the booth is the hard ceiling on daily output, GM spreads its enormous tooling costs — stamping dies, chassis engineering, powertrain hardware — across the Silverado, Sierra, Tahoe, and Yukon on one shared platform and across the Silverado EV and Cadillac Lyriq on the shared Ultium electric platform, so that every painted shell that exits the booth carries as much amortized development cost as possible. That same cross-platform sharing, however, creates a single point of failure on the EV side: Ultium battery cells come exclusively from LG Chem and CATL, so if either supplier is disrupted, bodies keep rolling out of the booths on schedule but have no battery packs waiting for them, and every Ultium nameplate across multiple plants stops at once.