I’m torn on that myself. If it was planned, a killer should want to be sure their DNA or prints are nowhere to be found. Like perhaps they would have been lured to a park where they’d be killed outside, with their car left untouched, and the killer would just drive away leaving only ballistics behind.
Instead, we have a scene where someone may have sat in the back seat themself, MG may have been touched and dragged into the back seat, someone drove their car to that apartment complex, someone else approached it, touched it, did a 1.5 second wipe of the door and the driver got back in and drove it again to the final spot.
All of those interactions with the vehicle can leave hairs behind, let alone prints. DNA on the seat, possibly, on the gear shift, turn signal, door handles, the back seat, did they touch the head rest, did they wipe down that child car seat in entirety after placing it on her, and so on. Way too many physical aspects to the interior where they could have left trace evidence behind. Doubtful the driver of the Kia spent 30 minutes disinfecting everything.