Monthly rent is only the most visible line. Insurance, maintenance, downtime, replacement vehicles, inspections, incident coordination and internal administration all shape real cost.
Start by separating duty cycles: users, daily mileage, cross-city work, parking and acceptable downtime. Compare offers on the same assumptions rather than headline rate alone.
For multi-city programs, include billing allocation, local responsibility and end-of-term rules. TCO simply puts easily missed operating costs back into one view.