Well I don't think it was a Diesel if it exploded by getting hit by a Christmas Tree...

My I sumit this excerpt from the movie Patton:

We'd send over a 20mm shell, the krauts would return am'. Their tanks are diesels. Even when we managed to hit one they kept on running. Our tanks... The men call them "Purple Heart boxes." One hot piece of shrapnel and the gasoline explodes.

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