One of my brothers had an F6 for a while.Fuel consumption was surprisingly good.Would do 10l/100 on a run from memory,pretty easily.
He had to take the turbo badges off it as the hoons always wanted to race against him at the lights.
Recently changed it over for a SS redline wagon,i think it is around a 6l V8.It uses a lot more fuel than the F6 ever did.

