Just wanted to raise the issue of the hire care = premeditation.
It seems to.
But equally, previous posters have discussed the difficulty of hiring cars without appropriate paperwork nowadays. Last time I hired a van, I had to submit my DL details online, also a Gov.uk code that the hirer could view my DVLA record.
We should remember that once police had the Astra number plate, they were able to move quickly, so he has, IMO, hired it in his own name or that of a close family member.
So he's not really made himself any less traceable for Sarah's murder, ultimately, than using his own vehicle.
So why use a hire car? Well, if regularly committing 'lesser' offences such as IE, perhaps LE see the database says 'Hire Car' when reviewing these and give up, without ever requesting info from the hire company (WC would know?)
Also to add, I feel EC is completely innocent, JMO, she may have gave him an alibi in the sense of 'he left for, and returned from work on X,Y,Z day', because she genuinely believed that.
Also to add, the only other thing I can link with Hire Car (if not Hertz, Europcar etc), is a garage courtesy car? But even then I can't see how this was arranged in a way that he thought he was making himself untraceable, as to do that you'd have leave a car with them for service/repair in exchange for the courtesy car,and that would have to be registered to a fake ID?
MOO