But what is his story and what statement did he originally give the police as witness to a serious accident.
As far as I understand, the empty fruit cider bottle had been attributed to Alice by the police as she had been told she had drunk that. It seems so far there is no story from George linking him to the empty fruit cider bottle.
If he told the police he went to Alice’s car only after his heroics, then people are going to start asking questions. As pointed out by @LillianGish Why after all his efforts in the river, would he pick up his empty fruit cider bottle and put it in Alices car. In fact why would he have put it in her car in an accident like that even if he went to her car first, surely the reaction would be to drop it and try to help not stow it neatly away goodness knows where in the car.
Given Alices defence has Alice believing she was not driving and Chris having serious questions about who else could have been in the car, they will want at the very least want to investigate any potential mitigating circumstances. Even Adam knows she has instinctively referred to us being in the car.
If George sudden claims that it was his cider bottle in the car, and it is known George ran to the (seemingly not visible) car when he heard the sirens and was alone with the car for a time before Alistair found him, they may then start looking at where he had been and how logical route wise it was for him to conveniently be at the scene of the accident. If he would have passed Alice’s car parked in the woods on the way there, phone evidence including positional, video evidence etc etc. The police would surely have asked if he witnessed the accident. Did Alice’s car pass him.
So I would think an unraveling (possibly creating pressure on George and leading to a confession) is one logical potential route to the truth coming out (if indeed it ever does).
Similarly with the car key and his fingerprints, very much depends on his story in the initial statement, but if the key was still in the ignition and his fingerprints on the key, he would have to make up more and more suspicious convoluted stories. Same with his fingerprints all over the steering wheel and gear stick and on the passenger seat belt when fastening Alice in. Also on the drivers seatbelt when fastening himself in and Alice in after dragging her back over. Let alone any potential vomit evidence on the passenger seatbelt indicating it was fastened.
It seemed obvious from his comments on the night that he had never been in the car before so he could not use that to account for the fingerprints.
Obviously if Alice had seatbelt bruising after the accident it would be clear she was in the passenger seat at the time, but presumably she did not.
Altogether even without video or Alice’s vague memories crystallising, I think there is likely to be a wealth of evidence for anyone looking closely enough, especially if triggered by initial circumstantial evidence throwing more doubt and suspicion on George.