Possibly dumb question, potentially obvious answer, but still.
When transferring characters from one vehicle to another, it is obviously permissible to leave a vehicle without operators. Thunderbird 2 can then pick up either Thunderbird 4 or FAB 1, operator or no, and transport it elsewhere. Is it then possible to fulfill the requirements of a mission that requires the presence of said driverless vehicle in that location? Nowhere in the rules does it state that a required vehicle need have a driver, but narratively it seems like there should be someone to drive it. Though maybe they have remote control devices or something. It is the Future, after all.