I purchased the ThinkPad X1 Carbon (6th Gen) laptop over a month ago and have been happily using Void Linux on it for the last couple of weeks or so. The battery on this thing is absolutely amazing - without any tuning specifically for the battery itself, I can get really great battery life.
I posted about my install on reddit and was asked specifically about the power usage. I said:
I keep firefox with ~15 tabs open and have a couple terminal windows open - that's my daily workflow, and I can get like 8 full hours on this laptop! Sleeping however is a nightmare. It doesn't support s3 out of the box and I have yet to try this patch to enable deep sleep - i'll report back when I do. When the laptop is suspended it'll last about 48 hours before it is completely dead (WHICH IS TERRIBLE).
However, my friend Mike showed me this tweet showing that the latest ThinkPad BIOS update added support for better sleeping on Linux! I really wanted better battery life when sleeping, so I jumped into trying to update it as fast as I possibly could - and in that process, I learned a lot and failed pretty hard at first. This is my journey into getting a good nights sleep on my ThinkPad with Linux.