I think you could make a ghost of a case for reasonable doubt, depending really on what you call reasonable. You hear hoofbeats. The prosecution says it's horses. If the defence can make a case that it's donkeys, that's reasonable. If they're reduced to trying to claim it's zebras, that's not reasonable. And of course many cases get into unicorns territory.
For me this is zebras but not unicorns. The two things that push me to zebras are the unexplained time on the journey (as the cherry on the top of the rest of his suspicious actions) and the fact that Suzanne's mobile phone was switched off while it was still in or near Thistle Street. It didn't ping a mast travelling away from there as you'd expect it to if she had got into a car and been driven away.
The thing I like about this case is that it was investigated honestly. It's not like the Luke Mitchell case where they decided "the boyfriend did it" right at the start and then simply datamined the evidence for factoids to support that theory. Yes I think they developed suspicions about Gilroy quite early, basically when they realised how much over-time the Lochgilphead trip was running (so probably about 10.30 on the evening of the 5th) and they definitely treated him as a suspect before he was cautioned and while he was still officially being interviewed as a witness, but that's not railroading. That's playing a bit close to the wire when you suddenly realise you may well have a murderer rather than a witness and you don't want to let any evidence go.
I don't know about the video of him looking under his car except what Darrell said. He said it was at the service station at Queensferry Road when he filled up at the very start of his journey well before any of the missing time happened. The SIO said to me that his car was definitely not damaged before be left. I don't know how he knows this but they did take the car and interrogate its computer as well as measure the remaining fuel, so that may be how.
What I don't understand at all is why he would have continued on what was a completely non-essential journey into the wilds of freaking nowhere if he was concerned about his car. From what Darrell and others have said of his character, this is not in character. His story is that he just wanted out of the office because everybody was dementing on about bloody Suzanne and he'd had it up to here with Suzanne. I don't find that terribly compelling I have to say.
I am a little wary of some of Darrell's facts because he has been talking to Gilroy and taking his word for certain things, and I don't think Gilroy is always telling the truth. For example Darrell said that the camera at the Green Welly didn't show the car's number plate because he just drove past, and there's no proof that was him. All the cops did was say, there's a silver car at about the right time, that must be him. However the SIO said (and I think I remember this from earlier press coverage too) that he had a red umbrella on the parcel shelf of the car and the red umbrella could be seen on the Green Welly CCTV image which confirmed it was the right car.
I forgot to ask the SIO whether Darrell's story that the "air fresheners" were just the blocks you put inside toilet bowls and he bought them for the house and they were found in the house was true. (No comment about whether they were still wrapped.) I suspect this may not be the whole story.
Sure, everyone has the right to put his case and try to persuade the public that he has been wrongly convicted. So knock yourself out sonny. But he needs to do a much better job than he's doing. His web site is cagey and obfuscatory, focussing on process rather than facts, and the crucial information, that is what the hell he was doing for three and a half extra hours when he was off-piste on that journey, isn't even addressed.