There are several things that just don't fit.
The Kenmore roundabout in particular. There is no reason that i can see, considering where ABC's body was found and where GBC's parents reside, why either vehicle would go through that roundabout if they were trying to be clandestine. It seems more practical to out to Kholo Ck via Rafting Ground rd. There's only 2 set of traffic lights to go through before u would be on your way from the BC home at Brookfield to Kholo ck. If u were to go thru the roundabout at Kenmore there are another 2 sets of lights u would have to go through ( kenmore rd-moggill rd intersection and Kilkivian-moggill rd). Being a local, it would seem a hell of a lot more risky to go via the roundabout as it's local knowledge that the stretch between the roundabout and Rafting Ground Rd is a regular spot that the cops like to hang out in and do RBT's etc. So risk factor of being pulled over going that way is MUCH higher. Also there are well known back streets that can be used to get from the BC home at Brookfield to GBC's parents at Kenmore via Brookfield Rd, avoiding the roundabout altogether AND rafting Ground Rd. The only reason i can see that someone would go thru the roundabout is to go toward the city/indro.
I also can't get my head around the most recent report from a witness re; small blue 4wd and white 4wd tailing it. It sounds as if they were heading TOWARD Kholo Ck, as the white 4wd has not been definitely identified as ABC's car with the Century 21 logo clearly on the back, that the witness would have clearly seen if they were behind the vehicles travelling toward Kenmore/the markets at Rocklea. At 4am, wouldn't that be pushing the envelope a bit to be disposing of a body? It would take considerable time to do so, and as lots of tradies live out here and head off to work very early, u would again run the risk of being seen post disposal. also why the parking lights? To have those on, there must be power to the vehicle, so no flat battery and keys must have been available to be able to unlock the steering wheel. But why just parking lights if the vehicle in front had headlights blazing regardless? More than a bit odd i think.