Here is my take: First of all, I assume the OP is based on the 2009 IMC, since Table 403.3 in IMC 2006 does not have the .75 cfm/sf exhaust requirement for repair garages.
3 non debatable points - IBC 406.6.3 requires mechanical ventilation in accordance with the IMC; IMC Table 403.3 requires .75 cfm/sf of exhaust; and IMC 512.14 does not apply due to exception 3.
So, can the overhead door be used as the make-up source for the required exhaust fan?
IMC 501.3 states in part "If only a mechanical exhaust system is installed for a room or if a greater quantity of air is removed by a mechanical exhaust system than is supplied by a mechanical ventilating supply system for a room, adequate makeup air consisting of supply air, transfer air or outdoor air shall be provided to satisfy the deficiency. The calculated building infiltration rate shall not be used to satisfy the requirements of this section.." SOMETHING has to provide make up air. It doesn't have to be a powered make-up air unit, it could be a louver with a motorized damper interlocked to open when the fan is running. So if it can be a hole in the wall with an open/close thingy, could the hole be the door opening, and the interlocked open/close thingy be the overhead door? Sure - an opening is an opening and a thingy is a thingy.
OK Dr. J, what about your usual natural ventilation rant? The issue is how is the minimum temperature provision of IBC 1204.1 satisfied along with IMC 401.3 requiring ventilation whenever the space is occupied. In this case, the exception to IBC 1204.1 probably applies :"Exception: Interior spaces where the primary purpose is not associated with human comfort. ". I would say the space's primary purpose is not associated with human comfort. Note that if you disagree, then even the louver with damper design would need to be show that there is sufficient heat to offset .75 cfm/sf. An open overhead door would be next to impossible to properly heat. But again, I say the min temperature requirement does not apply.
So, bottom line, can the overhead door be used as the make up air source for the required .75 cfm/sf exhaust fan - yes if interlocked with the fan to open when the fan is on. The Owner just needs to be aware that this requires an open door and operating fan when it is 4 degrees. If they can't keep their workers happy, that is their issue.
As a designer, I would suggest the much smaller louver and damper solution, and if the owner really wanted to keep his employees happy, add enough heat to offset the .75 cfm/sf. Overhead radiant heaters would be ideal. But this is not required.