Evening All
Regarding the earlier post about covering the seats etc in case of blood/body fluids.
I have given this some thought and believe that this gives a big clue as to his changing/evolving MO (and the reasons why other cases are possibly his, such as KT).
Fibres from the car seat where found on JR. This indicates that her body had been in direct contact with the car seat. That suggests to me the seat was not covered. Presumably this would mean he was not expecting blood in his car.
Going back to the KK rape - it was a blitz attack outside of the vehicle. But, after covering the victim with a hood and using cable ties to strangle her, he then put her in the vehicle and drove to KK cemetery to rape her. So she is alive in the back of the car being driven to a place to be raped. She is possibly unconscious, though I haven't determined this from the reports so far. But his "prize" is not to kill first, but to rape/assault instead. He wants her alive.
Moving forward to JR. I believe BE is MM. JR's facial expression shows she knew MM, maybe had met him earlier that night. MM possibly offers her a lift save waiting for a taxi, and she accepts. He gets his car, parked nearby, and picks her up. The seats of his car were not covered. Therefore at some stage he had to drive somewhere and somehow get her under his control. Perhaps a pretence of the car breaking down would give him the excuse to be outside and opening the back to access tools. Hood and ties are available again and he repeats the KK MO (or by now, perhaps SS MO too).
CG was different though, it didn't go to plan. Hence the smash on her head with a heavy weapon, which possibly meant no sexual assault.