Getting similar numbers on Debian/testing (which of course Ubuntu is very similar to); the main trick is to avoid going into s2idle suspend, because after resume from that it is up to 5 W (all 50% display brightness; for a few more checks, see Linux battery life tuning - #161 by Marten_van_Kerkwijk). I only wish resume from “deep” suspend didn’t take so long!
EDIT: link to solving problem of large idle power after resume from s2idle: Linux battery life tuning - #156 by technical27