Documents and an activity log on every vehicle
Files against a unit, filed by kind: title, lien release, bill of sale, odometer statement, inspection, registration, permit, auction receipt, recon invoice, insurance.
They live in private storage and are served as short-lived links. That is not a detail: a scanned title carries a VIN, the owner's name and address, a lienholder and often a signature, and in a public bucket the URL is the credential — permanent, unauthenticated, and impossible to revoke without deleting the file.
Alongside it, a per-unit log: what changed on the vehicle, when, and who did it. The log records that a key code or GPS device id changed and never what it changed to, so it cannot hand back the values the owner/admin policy exists to protect.