Regarding the map below, and presuming this was an accident:
If she took the green road in the photo, how would she have taken that sharp right turn to the path leading to the lake? It looks impossible to me without having to stop and do a three-point-turn.
The purple route also doesn't look likely as if she were driving on the foreshore of the lake, surely the lake would glisten and glint when it reflected her headlights. Plus the sandy mud would've felt different under her tyres.
So for me, the only likely route she took was the white route. Out of the parking, turn right and a straight run down into the lake.
MOO.
-Edited for typos.-
She absolutely could have gone the white route to the right of the map. The white route toward the other way was filled with water at the time (see all the previous maps posted from last night, from @otto and @OldCop et al). There have been a ton of maps posted over the past couple days.
That said, the question would be, “why?” And “is it likely?”
IMHO the most likely (if she did in fact get out there across that beach on her own, which is not yet substantiated but which I believe to be true based on what we know so far), is that she may have even thought she was on that road, or that she knew she wasn’t but thought it would be a quick hop to the fishtail part, where she would turn left, and missed it, and —not being able to see how close the water was to the right (in the dark, w/a drop-off), she continued on straight into the water (which was higher at that time).