Again, they're racers preparing to race, not preparing to crash. It's a sure bet the fuel cells were modified, but likely not for safety (although they still had to comply to the basic safety regs) but for racing - IE: made signifigantly smaller (no larger than needed for a typical race) and of newer/lighter/composite materials. My guess would be luck and the fact he was carrying as little fuel as he possibley could as the main factors for the lack of a fire... still, I am also curious what the tanks were made out of and where (and how big) they were located on that modified aircraft.
All I know is the Ghost was carrying enough fuel for us to get hit with a wall of intense gas fumes about 4-500 yards downwind from the impact. We had to move to another area because we didn't want to breathe all those vapors..
