They would get a warrant to search that car and property unless it was protected by international or LE treaty.
Could you elaborate on why you are "not feeling" the other possibilities?
Ok - if that's the case then maybe I can now rule out all the cars that came into that area? As the Police must have therefore forensically searched all cars and all those owners properties if they can get warrants.
Ok one-by-one why I am not feeling the other theories....
Walk Home - Not seen on CCTV, no apparent sightings, that is a long walk home, surely you would be seen, the walk is ruddy long, the walk would have 90% been in pitch black darkness. Nobody can walk home in pitch black darkness, maybe a stupid drunk person would and end up falling in a ditch?
Focus 12 - I cannot see some random person seeing Corrie, inviting him in or whatever and murdering him and then at some point loading his body off to dump somewhere. Cos surely they would not keep his body inside a building in which staff surely frequent and other people use, they'd also need a big old freezer to store him in.
Attacked within horseshoe - Likely to be witnesses to seeing or hearing something + would have to have a car there ready to take body away. Would be a bit random to do such a thing and do such a thing in a town centre surrounded by CCTV.
Something to do with someone he met that night - For the above reasons, how do you attack someone in a town centre and get rid of their body without anyone knowing.
He'd have to have been taken away on his own free will IMO though.....
For some reason I am now thinking he could have been bundled into a car by many people who were already sitting waiting in a car and taken away. Seems an odd thing to happen, but possible to do it quietly. Then the car burning attempts the next day could have been that group that may have bundled him into a car.
But then again wouldn't Corrie's DNA have been found in these vehicles that were in that area that have or are being investigated? - if so - or if that would have been highly likely to have been done by the police then any thoughts of Corrie being taken in a car can be ruled out?