Mark,
The have a little automated fire truck parked on a shelf in each section that will respond to the fire and put it out...:grin:
Seriously, I imagine they probably have some sort of fire monitor and halon type system, afterall, No humans go into where the cars are shelved so the system can be housed in a very low oxygen evnironment to reduce the risk of fire. Other than that, the risk is about the same as any other kind of parking garage. But it is a good point.
...Rich