Hi guys. This is my first post ever on any of these forums, so bear with me as I try to be cordial about all of this. I'm not out here to attack anyone personally or put myself out as an expert, but that being said, here's some thoughts on all of this.
The water temperature in the Missouri River right now is likely in the upper 30s to lower 40s. The coldest I've ever felt was 52 degrees in the Pacific near Monterey, CA, and I was barely able to wade into it for more than a few minutes before I had to get out or risk losing feeling in my toes. Imagine the sheer amount of shock your central nervous system would have to endure in water that's barely at 35 degrees. At that temperature, it would literally only take 3 to 4 minutes, at the most, for hypothermia to set in. If she's impaired by a foreign substance that affects cardiovascular output, it could take even less time.
This is quite accurate. It only takes 6 inches of moving water to move a vehicle off of a roadway (which is why public safety is always telling people not to drive over roadways submerged in water). If the ramp is slick (condensation can, and does often freeze in the winter, making roads and hard surfaces icy), it has a steep enough incline to induce motion on a vehicle, even with the brakes applied, and once it hits the water, it's game over.
The curb weight of a 2015 Ford Focus is 2,935 to 3,055 lbs. You do the math on that one.
This to me is the most plausible and likely scenario. She's disoriented in an area that is essentially dark, and finding landmarks at night in that area, amidst all the trees and hills is practically impossible.
I'm not sure myself, really. And I don't think it's impossible. We won't know if she was on anything until toxicology reports come back (and who knows how long that'll take in Missouri; the average wait in Kansas is several months, but our state is also broke beyond comprehension, so there's that), and if she had underlying psychiatric problems, the compounds she'd taken could've amplified those. And people make snap decisions all the time (e.g. everyone has made an impulse purchase at one point or another), so while I don't think that's as likely, I don't think it's unlikely or impossible either. It's a valid theory.
I would wager that most of the windows that were broken out upon recovery were broken when the vehicle was turned over as the current carried it downstream. It's worth noting that they pulled the vehicle out of the river nearly 600 feet downstream from the ramp itself, which would allow for it to turn over multiple times over two months. It's also worth noting that they acknowledged that the vehicle sustained some damage during the recovery process and windows likely were broken as a result (the bank is covered in large stones...).
As far as the trunk goes, that's anybody's guess, really. My gut says it was probably already open when the vehicle went into the water, but that begs the question of why it was open, and the most likely scenario is that the latch failed, or distortions to the vehicle body in the process of overturning in the water forced it open.
I feel like I know the metro area "well", despite only having lived in it for 6 years. I live in Johnson County, and know parts of it like the back of my hand, but those "parts" only account for about 1% of all the county itself. It's not impossible for people to get lost in their own metro area, especially if they don't traverse every single part of it on a routine basis. I mean, seriously, how well do you know every single part of your home county? I lived in a county in western Kansas that has only ~45,000 people in it for 20+ years, and I'm still finding new things about it that were always there every time I go back. Just because you can't believe that someone could (and would) get lost in their home territory doesn't make it impossible or even implausible.
"The absence of evidence is not evidence of absence."
Occam's Razor is the standard upon which investigations are built. It's not foolproof, nor is it 100% accurate, but it's the most reliable method, and thus far has the best track record.