I am hoping that finding her car will either lead LE to her (or she is with the car) or to a person or persons that know what happened to her. While I know she has a number of people looking for her and her car I don't know if they are checking or have checked everything. I brought up earlier about the parking garages where you either need to pay or be a guest, employee, or student. I did so because there is no shortage amongst the people looking for her that don't have two nickels to rub together as you see them either needing gas money, their phone is shut off because they have run out of money, etc. Also, there may be an assumption that people who use the garages would notice the car or that someone wouldn't park a vehicle there. So, for example, a hospital parking garage (which is open around the clock usually) would be a good place to leave a car because there are too many cars that come in and out of there that nobody that works there pays much attention or they never go all the way to the top of the garage, etc. Is there long-term parking at the airport? Are there any Park N Ride lots?
So, I worry about assumptions searches may make at the expense of absolute thoroughness. I am not being critical of their efforts by any means. It is human nature to make decisions based on assumptions and especially when there is a perceived or actual risk based on time which certainly was/is the case here. I am glad that they are taking a more organized approach. I would hope that they have engaged SAR groups in the area but I don't see clear evidence that they have.
Since the reward hasn't caused anyone to come forth with information they should probably reduce the reward and re-purpose some of that money to obtain some search assistance. Buy some time from someone with a plane, perhaps, that can look for a vehicle as just one example. Yesterday, in Saline County (far south Illinois 5/6hrs from Rockford) a road crew doing mowing along a road discovered a car with a body in it in a ditch that could not be seen from the road. From reports the car had been there for some time e.g. not a very recent accident. That story illustrates just how hard it may be to find her car or her.