This is probably nothing, but I was sleuthing around on Google Streetview and came across another Landrover Discovery, parked on one of the unnamed side-streets of Bryn y Gog. This one is a silver/grey colour. Otherwise, it is very similar to the blue one that has been in all the photos.
Obviously, the images will be from at least a year ago. I am somewhat confused about the vehicles that may be of interest. From what I can gather, the kids said it was grey, not blue (or were they talking about the van?). Something doesn't quite add up anyway.
This should take you to the very spot on Bryn y Gog, by the phonebox and the bus shelter, where you can see through the walkway (looking west). The spot is approx 80 metres north of the A489. If you aren't standing in this exact spot and looking in this exact direction you cannot see this silver Landrover.
Here is the link. It is a Google Streetview shot, so it may take 30 or 40 seconds for the page to fully load. If it doesn't work, hopefully you should be able to find it from my directions:
https://maps.google.co.uk/maps?q=machynlleth+map&hl=en&ll=52.5925,-3.841158&spn=0.000864,0.002411&safe=off&hnear=Machynlleth,+Powys,+United+Kingdom&gl=uk&t=h&z=19&layer=c&cbll=52.5925,-3.841158&panoid=qNPfY0GvrS5rDgR3DRl3HA&cbp=12,80.91,,1,8.02
Having found this vehicle, I then used Streetview to walk around to where it was actually parked. You can get closer to it, but the view is not so clear, close up, due to other cars on one side and the fact that the only other image is taken from right in front of the car, making it difficult to be sure it's a Landrover Discovery.
Google blurs out registration numbers, but in one of the shots they have been a bit lazy. They haven't bothered to blur out the reg number of the Landrover, as the shot of the plate is at an acute angle. Using the image zoomer, I got this shot and some of the numbers are visible.
I think the reg is ? 369 ???, with the first character possibly being a H. Here is the link:
https://maps.google.co.uk/maps?q=machynlleth+map&hl=en&ll=52.592526,-3.840457&spn=0.000864,0.002411&safe=off&hnear=Machynlleth,+Powys,+United+Kingdom&gl=uk&t=h&z=19&layer=c&cbll=52.592526,-3.840457&panoid=CaiJ8anYZSkPLMjgx0iNvg&cbp=12,262.41,,3,13.88
I guess it's a tight knit community, so I would imagine that this vehicle would have been quickly proven to be not involved, if it's still on the estate? Maybe it isn't though. Did MB ever own a previous Landrover? Could it be this one and though replaced, perhaps the old one was kept for parts and is still a runner? He had girlfriiends all over the estate, from the sound of things, so could have been a regular visitor when the Google cameras came through the town.
All very far-fetched. The more the story drags on, the less I am inclined to automatically assume he is the guilty man, anyway. Something just doesn't add up. He's no way a typical suspect. The crime just doesn't make sense, in any way at all. I would be more inclined to believe that if he is in any way guilty, or knows what happened, that there is someone else involved.
It also seems plausible that he might have enemies in a town like that. He's an outsider who has put it about a bit with the women around there. I agree with the previous poster that he could easily have been looking for her, dressed in waterproofs and acting independently. Obviously, he seems the most likely suspect but, as I said, it just doesn't add up properly.