Just had an awful thought, but unfortunately it’s possible. When she got in her car to drive home, maybe she still had leftover alcohol (didn’t they go to her car to charge phones and get more alcohol earlier?) She doesn’t want to drive around with it, and she’s planning on being back there the next day with friends. So why not stash it in the lake overnight where it’ll be safe and cold? Maybe instead of heading home directly, she drives around the lake to find an out-of-the-way spot, but it’s dark, they’ve just had torrential rain the previous two days, dirt road shoulders may be soft. Maybe she drives too close, or isn’t expecting the water level to be where it is? A vehicle can sink completely in less than a minute, even if starts out very close to shore. They’ll tip and float first, get carried to deeper water, and then sink. Very quickly. Her phone might have gone offline finally at that point. The sediments in that reservoir are probably 10ft-50ft deep, and could swallow a sunken vehicle, making it very hard to spot visually. I think an oil or gas slick shows up at some point if a car is under water, though, and so far no reports of that.
