I think that the plaintiff will have to work hard to remain calm and truthful during testimony. It sounds like he is more easily frustrated since the crash, which will work against him.
Additionally, his memory of the events that day has changed. For example, his testimony of being unconscious for 45 minutes hasn't been independently confirmed ... yet. Doesn't that detail come later? People who have been unconscious don't suddenly come to and claim - hey, I was unconscious, what'd I miss? I'm not a medical professional, but I don't think unconscious people know that they've been unconscious unless told.