I get around 48 mpg overall in my daily ('00 TDI Jetta) and we have a new TDI on order. For me, acceptable fuel economy is a moving target. If I'm buying a FWD commuter, I want high 40's because I know that I can have it. But if I am looking at 'fun' cars, then I am willing to drive something that gets half that. I'd be willing to take RS4 fuel economy to drive an RS4.
My truck gets like 12.5 mpg overall, but I hardly drive it (Though I do have to take it to OH this weekend
).