If those things crash and catch on fire, I bet they will burn hotter than the surface of the sun.Doubtful. Aluminum will burn if you get it hot enough, but there's nothing in a truck that will burn hot enough to get it started.
I grew up around junk yards and body shops, and have seen lots of burned vehicles. Aluminum parts just melt.
Ground aluminum is what burns ferociously and is not as hard to light. I think that is what some people are thinking of. Since the inside of the combustion chamber gets pretty darn not, and aluminum engines don't immediately vaporize is proof that solid aluminum won't burn from any kind of crash.
If it would, most race cars would explode, as many of them are made out of titanium and aluminum.