The simplest answer I can think of is that the digital data shows the hire car was never in the area of the woods. If only his own car ever went there, and Sarah ended up there, then at some point before 8:30am he had to have moved her to his own car.
I don't think he'd ever have taken the hire car home either. I think he took his car to somewhere near the car hire business, took the hire car to where his own car was parked at 1am and switched to his own car, took his own car home, then went back at 8:30 to collect the hire car and return it. I wonder if his wife gave any details of his comings and goings
Yes that is sounding more likely- good point. He would have gone home in his own car (as he left in his own car). And that would explain why his wife didn’t see the hire car next morning when she went to work (as per annpats deductions).
So that would make sense. Transfer the body to his own car, leave the hire car parked up somewhere, go back next morning and take the hire car back ftom where he left it.
The confusion with that though is it’s stated that cameras tracked the Astra and it was seen at 1am at Tilmanstone - which is after he went through Dover/past hire car place - and when he was nearly home. And that they know he was home by 1.30am (although that could have been from cell data rather than the Astra seen on camera as probably no cameras near his home.
So to work this out we need to know if it was actually the Astra that was seen on camera at Tilmanstone.
I think it did say that which suggests he did go home in the hire car. Maybe he put it in the garage snd closed the door leaving his wife’s car out on the drive ready for her to go next morning so she wouldn’t know any different.