Fuel economy is poor in the single turbo A7 so must be miserable in the bi turbo! I know it is a 6 pot diesel but BMW manage to get 10mpg more out of a comparable engine?
Mine does mid 20's round town, very low 30's on a run. I not drive it very hard but am no slouch either. It's massive weight is its downfall.
......as well as crap MMI lol