I know some time ago there was a discussion about how to stat a tank, but if I remember correctly, that was more for statting a single vehicle.
This thread is not only for ways to STAT the vehicle, but how to handle combat between pilots/crew. I ask due to the discussions on various kitbashing discussions as well as the period-specific discussion.
The only way I am aware of offhand is the version in Strands of Fate (not exactly 100% compatible with DFRPG), where you "stat" our a vehicle by doing the following:
1) Decide what the vehicle is.
2) Determine Size (impacts cost, equipment usable, cargo capacity, etc)
3) Give it 1-2 Aspects (think High Concept)
4) Assign "Abilities" (vehicles have 7 skills to select from/use. Roll this skill. Skills include Crew, Maneuverability, Structure, Sensors, Speed, Systems, and Weapons).
5) Specialty Aspects (more Aspects to flesh out what it can do)
6) Vehicular Advantages (make it more expensive, add special abilities; think Powers, but really nitpicky, like requiring a "mobility" power to be able to move at all)
When taking an action, you used the skill rating of the vehicle (Maneuverability for dodging, for example) and not the character's skill.
It has it's own stress boxes and consequences, and acts as a character in all regards.
The only other thing I can think of is making a sub-character, so to speak, by using the Extras chapter of Fate Core.
Does anyone have any experience with this, or any ideas to offer?