The BMW 5-series is really a remarkable line of automobiles. The size is just right for four people and you can squeeze an extra person in the back seat without incurring too much pain.
Performance is excellent and it has nice luxury.
The knock against the 5-series, of course, is that the cars aren't cheap. But when you tote up what you get after you plunk down your dollars, to many people the car is worth it. The six is not what one would expect in a luxury car, even a low-end luxury car. But that's what Mercedes puts in its luxury cars and that appears to be the norm in Europe. For the BMW the six is probably adequate.