dude ... you dont' drive 160km/h on the highways, the fuel
consumption will go up proportionally of course .....
to give you an idea .... at 180km/h, my civic drank almost half
a tank, in less than 10 minutes .....
if you're looking to save fuel ... cruise at, say, 100km/h ....
and you can get from bangkok to petcha on a single tank ....
i think i'm too used to my old bike
i actually felt 160 was slow already 
2001 camry for 18K!!!!