Apologies if I'm mentioning things everyone's been through before, but I think the car was left, just as though he'd just crashed and got out the vehicle to check the damage.
What puzzles me most is that his watch was placed underneath his tshirt, then his shoes etc all apparently found neatly on the ground. In the opposite direction are the other items. It was apparently a new moon and essentially pitch black. How could you lay your clothes and possessions neatly on the ground, with small gaps in between in complete darkness? These items were quite a distance away, so I suppose car lights may have worked. Were the lights damaged at all?
I'd like to know if his family and friends were able to comment on whether this is how he usually got dressed. Did he usually chuck all his clothes on the bed, or get items out one at a time, or did he create neat piles of clothes as seen in this incident?
Maybe it's OCD. I would have possibly expected in this instance for the piles to run as per getting dressed, so maybe underwear first, then his tshirt, then his trousers, his belt, his shoes then watch, or similar to that. He may have had a different order of getting dressed, (linked to OCD) as reflected in the order of the items laid on the ground. Putting on his watch after he's put on his tshirt makes sense too. The toiletries were found with the other items, which possibly messes this theory up, but I'd be interested to know if he was one of usually men, who use deodorant after getting dressed, by just pulling their tshirt up.
Once dressed, he'd collect any items he needed depending on his plans for the day. For example I get dressed in the bathroom or bedroom, then head downstairs and collect my handbag and any other things such as shopping bags, basically anything I need and then I leave my home. This may account for the other items having been left in a different location. Again (and I apologise for possibly over labouring this point), this would make absolute sense if he had OCD or even anxiety. Routines are comforting.
It may be entirely irrelevant, but I would like to know if anything does ring a bell. It would possibly aid the determining of his mindset.