I get 400 miles out of a 93 octane tank (with 10-20 miles left on the computer) on my 328 xdrive wagon with 6MT with.
I have driven 350 miles per tank on the two 328 xdrive sedans with AT that I have had as loaners.
All cars used 93 octane gas with 10% ethanol and had less than 5k miles on the odometer. Same roads and driving conditions.
If I'm not mistaken the wagon is 100 pds heavier than the sedan. Dunno about MT vs AT.
2011 e88 6mt
2012 e91 6mt xdrive