The following is just MOO and speculations assumptions based on nothing else then what i have read or watched here on YouTube etc.
In other cases i have read about, the killer would dump a body or pick a killing spot in the opposite direction to where the killer lives. So if and or when the victim is found and there are alot of LEOS in the area, they will be farther away in opposite direction whatever to where the killer lives......But this killer was different in this aspect. For whatever reason, and it could have been it was daylight and not nighttime which is more risky to travel with a kidnapped person during daylight for obvious reasons. But this killer drove took her/left her in an area that would be on his way home. Perhaps because it was daylight, he felt better more confident traveling towards home then going in a opposite direction. Where her clothing and remains were found i would guess the killer at the time lived right around that area. Probably no more then 5 too 10 miles a relative short distance regardless where she was found. A killer that knew the area where she worked the town and so forth. But lived outside the general area. Around 5 or ten miles outside there and where she was found, so perhaps 10 20 miles from her job to her place of foundment.
As far as the white car with the guy on the day before. I wondered myself why that person never came forward to say hey that was me, i was there that day to just let it be known it was him. But he never did as far as i know, WHY? Could be any reason from not wanted to get involved or perhaps was the killer or perhaps it was an out of town car or had a hatred for LEOS. I don't recall anyone mentioning the plates. It could have been a rental car just passing through or whatever. But i still don't think that was the killer.
ADD ON...ill go with a 50 mile radius from where she was found. To give the killer an hour or so to drop the body and go back to where he was staying. Plus at the time, this area was more rural and open spaced out.