Most grey fleets are managed for basic mileage compliance, but the real cost lives in the shadows. Hidden insurance gaps, overclaimed mileage, downtime, admin overhead, and emissions often add 40–60% on top of visible reimbursement spend—turning “cheap” grey fleets into silent profit leaks. This post breaks down a practical Total Cost of Ownership (TCO) framework and shows how GPS telematics and verification tools like Fuelshine can turn those invisible costs into measurable