The Space Shuttle Challenger exploded shortly after take-off in January 
    1986. Subsequent investigation determined that the cause was failure of 
    the O-ring seals used to isolate the fuel supply from burning gases.....

    NASA staff had analysed the data on the relation between ambient 
    temperature and number of O-ring failures (out of 6), but they had 
    excluded observations where no O-rings failed, believing that they were 
    uninformative. Unfortunately, those observations had occurred when the 
    launch temperature was relatively warm (65-80 degF).

Let's look at this question "how bad will that fire be for persons and property involved?"

You look at your 12 crashes where fire occurs, so (e.g.) 6 crashes. Of 6 crashes 3 were accompanied with injuries. All 3 crashes that were accompanied by electrical fires and injuries occurred was when the car's speed was between (e.g.) 40mph and 50mph. Does that mean when the speed is not between 40mph and 50mph, people won't be injured when there's a crash and a fire? It means nothing like that but it's too easy to make a wrong conclusion; you're skipping all the other data where injuries and/or fires happen independently of crashes.