I am going to PCS soon and was looking at selling one of my two cars. Both are fairly new, low miles, clean, well-maintained, etc., everything I thought fellow USAA members might be wanting in a used car.
After uploading a bunch of required photos and answering the few vague questions about vehicle condition, I listed both on USAA to see what would happen. What did happen was nothing.
Instead of making cars available to other members like it used to, the "service" now tries to get local car dealers to buy the car for cash. Only after no dealer makes an offer, as happened with both of mine, can the car be posted for sale to other members. Even then, there seemed to be no provision for entering any custom information into the ad and the ad gets buried under all of the ads from dealerships. Even if one sorted the search results by model year, the member ads come up at the very bottom of the list, out of sequence.
It's pretty clear that TrueCar and the USAA Buying Service have no interest in helping USAA members sell their cars. If you need to sell a car, don't waste your time with USAA, use Auto Trader or take it to CarMax.