Ive got a 09 G6ET the car is tuned, and on the clock it sits at 16.9l/100k whole tank before the computer warns about 20km left in fuel, im getting around 320-350km per tank. I dont do a lot highway driving, but I do drive to work 3am everyday, there is no traffic, and sometimes, M4 and things like that, highway never more than 30 mins. do a lot of city driving, but not really peak hour traffics. I've been like this 16.9 for a while, and its not dropping down. is there any concern? ive asked people around , their tank always do more than 400kms. ive been using BP Ultimate all the way, sometimes other 98 fuels, not much difference. Need advice.