As I remember, the COD article stated something about the violent acts occurring within a short period of time. Here it is:
Of course, that is a subjective statement and possibly only made to make family feel better about what MC had to endure. {Also, although I think they would, are they considering all three injuries as "homicidal violence"?}
Still, an attack while going through the car wash could be plausible IF we forget (or disbelieve) LE's statements towards the condition of MC's car. Almost any attack, (and certainly what is described as the COD), happening inside her car would leave a significant amount of evidence behind. Add to that, an attack while going through the car wash adds a high degree of danger towards getting caught, making me think it would only be done in a non-premeditated murder situation, (or as a last resort - the car wash being the only opportunity the murderer has to be semi-alone with MC). Still, where would the suspect get the RUMORED murder weapon which caused the blunt force trauma? A hammer is not likely to be found in MC's car, so murderer would need to have it on them, meaning we are back to premeditated, which again doesn't really make sense to premeditate for a murder to happen while going through a car wash.
I'm going in circles with this one. It's not impossible, but I believe we have to throw away some "facts" as LE has reported them. So many it becomes implausible IMO. With the phone off / not receiving calls as early as 4:15, (possibly indicating MC was already in trouble), doesn't really affect many of the theories I have read. Although, if you are going with the theory that MC went willingly out to CB, with her cell phone leaving service area as the reason texts and calls weren't going through, then that leaves for a tighter time-frame. Every other location we know of, (or has been rumored of), is only a few minutes from downtown.
So here's an idea about some of your great devil's advocate work (thanks!!!)
I don't know about you but I keep a very large flashlight (heavy metal one) in my car to use for light but also to hit people that scare me on the head----so that could be a weapon to hit her on the head if she had something like that. Second, maybe that blow did not lead to any blood but left some other evidence when the perp moved her out of the driver's seat (hair, etc.). And maybe it is THAT evidence that made LE worried when they found her car up at PC and suggested that something more had happened to her than disappearing. The idea of pre-meditating an attack in the carwash totally makes sense to me---I can picture that being a perfect (5 min. of no one being able to hear or see anything) set up to plan----as long as you know that you can get her out of the driver's seat.
It explains how she could get incapacitated in 15 minutes IF and I mean IF we are talking about a 15 minute window between an Uncomfirmed sighting at 4 PM and 4:15 unanswered text by JV (although we still don't know if his 4:15 texts went right to voicemail). You are right that this seems risky for the perp and it seems like it would require great strength---I agree.