At the end of Back to the Future 3, the DeLorean is destroyed when struck head-on by a speeding train.
I'm sure some, if not total destruction would happen to the car. But would it really be blown into a million pieces like in the movie?

I apologize in advance if this myth is already busted and I somehow missed it.

You're probably right. It's unlikely that the results would just be confetti, but a few larger chunks of twisted scrap metal. The car had stopped so the speed of the train was all that would be involved. The locomotive portrayed would probably only be traveling 40 mph or so and the results would be more on the order of what happens in an urban grade crossing collision. It wouldn't be the first time real world physics have been exaggerated for the sake of entertainment in a movie.

I don't know if this would be a factor, but don't forget that the DeLorean was (to my knowledge) the only car constructed of stainless steel.

To quote Doc in BTTF 2: "Biff's in a '46 Ford. We're in a DeLorean. He'd rip through us like we were tin foil."