Thanks, k4kathy! I do remember reading that post now. Feeling silly for not looking back through this very thread.
Been looking high and low for specific info about the wreck, and this is the only thing I've been able to find:
http://newsok.com/oklahoma-girls-mysterious-disappearance-prompts-massive-search/article/3882613
Not much to go on, but could this have been enough impact to deploy the airbags? Depends on how sturdy the fence was, I guess. And the small trees. On this type of rural acreage, barbed wire fencing is very common because it's the most economical choice. Sometimes you'll see hog panels strung between the same type of metal posts that barbed wire is strung on, depending on what you want to keep in (or out).
I wonder if it was a gate and not a fence the car went through? If so, gates are generally built more solidly than the fence itself. A good solid pipe rail gate is easy to swing open and shut when you need to drive through it and will last a long time with minimal maintenance. The reason I'm wondering is because of the gate that's supposed to be at the end of Long Hollow Road, and also because it's hard to see $14,000 worth of damage to the car if it just ran through barbed wire and some saplings.
The angle of impact would be a factor too, I suppose, whether the car hit whatever it hit head-on or at an angle. Or could the car have skidded sideways through the fence? Because that could make the side-impact airbags deploy, and Molly's DNA might be on one of them if she was riding in the back seat.
Honestly, I know nothing about what it takes for an airbag to deploy and am hoping some who does will come along and discuss the possibilities with us.
McSpy, your theory is on my shortlist as well. If [the driver] did flee the scene, leaving Colt and Molly to fend for themselves and they died as a result, he's still just as responsible, IMO.