I am still trying to catch up, and I apologize if this has already been brought up:
From early on, I've felt the perp's vehicle had a stolen plate(s) at the time of Yingying's abduction, and I also think that the Astra does not belong to the perp, but rather it was also stolen. LE has had 2.5 weeks to look into the current owners of Astras, recent/current sale listings and past sales. It just seems to me if the Astra actually belonged to the perp himself, family member or a friend, they would have identified the person and interviewed (or at least try to) him by this point. And that may be what they are doing as we speak, and they just haven't released any info.
I also think if the perp dumped the vehicle at a random location, it would have been found by now, with LE releasing that information to the public. The legitimate owner would have been notified and interviewed. They may also be doing this right now, while keeping that information close to the vest.
So
if the Astra was stolen, as well as the plate(s), where could the perp have hidden the vehicle?
One possibility I thought of is an old barn or a large tool shed that's currently not in use. If the perp is local, he would have relatively easy access to such structures, as the UIUC campus is located in a rural area. Say if the perp inherited or purchased a farm with a barn or a rural property with a detached garage or a pole-barn-type structure on it, he could hide the car in there at least for a while. These types of properties would allow the perp to engage in criminal behavior (keeping someone hostage or worse ...

) without neighbors thinking anything of it.
My late grandma, who lived in a 100-year-old farmhouse on a 280-acre property in southwest Indiana had an old barn, old shed and a rental property on it. The barn sat empty after my grandad passed away in '76. The rental property sat empty after a pair of sisters moved out to move into a nursing home in the late 80's; my grandma couldn't keep up with the maintenance it required, and it didn't make economic sense to hire someone to fix it up. In the shed, she kept all kinds of stuff she just couldn't let go of for sentimental reasons, including a Ford from sometime in the 50's that my uncle worked on when he was in high school in the 60's. Since there was nothing she really needed in there, she would go inside the shed maybe every couple of years, just to check on it for leaks in the roof, etc. Her closest neighbor lived at least two miles away.
A property like that would be perfect for hiding something for a long, long time, until the perp slips up, or re-offends and gets caught.