I agree with much of what you write. We will never really know what happened or if she was a closet drinker and pot smoker and had just been lucky so far. She sounded very responsible when it came to the children.
One thing that got me thinking she wasn't drunk or passed out was the witnesses saying she was driving straight at that speed. That's not typical for a drunk person. They lose coordination. And at least one of those kids was old enough to be screaming they were going the wrong way. Why didn't she listen? Its almost like she was committing suicide.
The parents of the dead girls also said Diane was a wonderful, responsible, person, so whatever happened must be so hard for those families to not know.
Thanks for reading and your comments. You posed some good thoughts. Things to make me think.
I've followed up as much as I could on the case since first stumbling on the documentary 5-6 years ago. Nothing new came up.