Just thought I'd add what I have learned about VCDS-Lite to this thread, rather than start a new one. I wanted to try something on the cheap to see if I find it useful first. Although Bluetooth dongles and Torque app are dirt cheap, it didn't suit me because I don't have an Android device with Bluetooth and didn't fancy getting Android emulator to work on the laptop. So decided to try the free VCDS-Lite s/w from Ross-Tech with 3rd party USB-to-OBD2 cable.
VCDS-Lite version 1.2 is the latest available from Ross-Tech as a free download. It has many limitations compared to the paid-for versions of VCDS s/w. The limitations are listed on Ross-Tech website. The ones I noticed are that auto-scan is not available - you have to scan each module individually, and some fault code descriptions are replaced with reminders that this is free software. You can google the fault code numbers for clues instead. VCDS-Lite installs and runs fine on my Win 7 Pro 64 bit laptop.
I bought this cable off ebay
https://www.ebay.co.uk/itm/191563446821
I suspect all of the cheap ones direct from China that look like that are probably exactly like that, based on the same Chinese chipset: CH340, LM339 (so not FTDI based and not opto-isolated). The cable came with a mini-CD with VAG-COM release 409-1 s/w which was intended for Windows XP and did not work on Win 7 Pro 64-bit. There were some how-to instructions for installing driver software but these were irrelevant because they referenced FTDI chipset and did not mention CH340. Btw I think opto-isolation is just belt-and-braces to protect the laptop USB port, so did not worry about lack of it here. To get this cable to work with VCDS-Lite on my laptop I had to rectify some snags:
1. Windows auto-installed some generic Microsoft CH340 driver dated 2009 but this didn't seem to work. I googled CH340 driver and installed that instead. It turned out to be a more recent one signed by the chip manufacturer wch.cn and dated 2014 (CH341SER)
2. I had to make sure the cable is assigned to a COM port in the range that VCDS-Lite expects (COM1 - COM4). If Windows auto-assigns a higher port number (check using Device Manager), then reassign manually to a free COM port in COM1 - COM4 range (use Device Manager for this also).
3. In VCDS Options, make sure the right COM port is selected.
4. In VCDS Options, change Start Baud from default 0 to 9600. Before I did this, it would work with all modules except Engine, I was getting "cannot sync baud rate" error.
So now VCDS-Lite reports that all is well and latency is excellent. I read CCU fault codes and reset them. Sadly some have reappeared since (intermittent "can't lock" and "won't de-safe" from one of the rear doors). I was happy to learn that the Engine management unit only reports one fault - intermittent lack of comms from A/C controller.