The "hicar" subfolders have always existed on the http firmware site, and the firmware files within have never worked on the Carlinkit adapters we have (despite having the same "U2W_Update.img" file name). The only firmware files that work on our adapters are/were the ones in the root of the date folders on the site, e.g.
http://112.74.112.110/download/2020-03-07/U2W_Update.img (those files have since been deleted--wish I had thought to archive them all!)
As I recall, on the 112.74.112.110 site there were date folders for every single day (or almost every day), and there were "tmp" and "hicar" subfolders within each one. But only some date folders contained a U2W_Update.img in the root--those were the ones we could flash. On the site there were directories/firmware files dating back to late 2019, maybe even earlier.
Why Carlinkit removed the updates for our adapters, I don't know. I can only speculate that they did not want us flashing them--maybe that site was only intended to be used internally or for beta testers. Maybe they just didn't want to have to support users trying to upgrade via USB. But I am pretty confused as to why they've never posted a firmware file newer than Jan 22nd to their auto-update server. In my experience the March 4th firmware is far and away faster and more reliable than Jan 22nd. It really makes me wonder if the person/persons who administer that server either died or quit during the coronavirus epidemic. It's a long story but there was also an "activation" server set up for people who used 2019-era Carlinkits to upgrade to the 2.0 firmware release in mid December (to the person who was wondering, references to version 2.0 are talking about the new-generation firmware, not hardware). I think they set up the activation process to deter counterfeiters. Anyway, it was normally a seamless process. You'd flash the 2.0 firmware, connect to 192.168.50.2 the first time and it would automatically activate the adapter. Well, after late January that process stopped working entirely. Anyone who tried to upgrade to the 2.0 firmware after that was locked out (the car's display would say "Activation required" and the 192.168.50.2 site would ask for a username and password). To this day, the only way past that is to contact Carlinkit support and manually activate by sending them a log file, at which point they give you a unique login to enter on that page.
Could just be coincidence, but their operations/server infrastructure hasn't ever really worked or been updated since late January. It makes me wonder if they can't access it to update/fix it. Just speculation on my part--I could very well be wrong.
Anyway, I'm happy for the most part on 20200304. Does anyone else experience Siri's voice getting cut off when announcing what music you just asked her to play? Like if I press the steering wheel button and say "Play Rubber Soul by the Beatles" she'll say "Now playing, Rubber Soul by the Bee--". It's like it cuts her off before she can say the last syllable. I've never seen anyone else mention it (and I think I even brought it up here in a previous post), so maybe it's just an issue on Ford Sync3 cars. Obviously not a big deal in the scheme of things, but more of an annoyance I hope will be fixed at some point.
Overall I am very pleased with the purchase. I'm still sort of amazed each time the CarPlay interface pops up while my phone is in my pocket. This adapter finally turned CarPlay into an everyday thing for me. Previously I only bothered to use it on longer trips or when I needed turn-by-turn directions. Now it's basically become my car's de facto interface for maps, music, calls, texts, etc.
