I have the same camera and I'm having similar adventures trying to find an optimal combination of settings. At the moment I'm trying it set to Shutter Priority mode in Exposure, with 0ms - 7ms shutter range, and noise reduction just a couple points past the bare minimum (set to 10 in my case). Moving objects are trailed by ghosting. In color mode, it gets much more pronounced, so I'm sticking with B/W.
I've also experimented with manual Exposure settings, which lets me set a Gain range on top of the shutter speed. Reducing Gain brings down noise, but also makes even my very bright scene too dark. For reference, the attached photo is from a camera two stories above my Dahua, a Bosch 7000 Starlight, showing how much white light I've got with the parking-lot floodlights plus spotlights. Ideally I'd use a shutter of 1/200th or 1/250th, gain at 50 or less, and run full color, but my 5231 can't do it. My 5442 probably could, or my Hik DS-2CD2385G1-I, or my Bosch 6000 Starlight. The reason the 5231 is even being used is the 13.5mm lens, it has the range for what I am doing.
Going back to your own scene, they were walking quite fast across the scene. If they had stopped to try opening the car doors or look inside of it, your camera would have had a much better chance at identifying them.