If you load up a car with gasoline and then try to blow it up, it causes a fireball. It's not the kind of blast that's going to propell shrapnel, so why are they loading the cars up with screws and nails? In fact, unless you've got just the right mix of gas and air, there's a decent chance that it's not going to ignite at all.
A waste of perfectly good gasoline if you ask me.
Owl_Eagle
If what I just wrote made you sad or angry,
it was probably just a joke.
Only by the mercy of God no innocent people were injured or killed regardless of how low grade the potential murderous morons are.