Hi There,
We tow a Bailey Series 7 Provence (1490KG) with our 58 plate 520D M-Sport Touring (manual). We are more than happy with the car / van combo and have towed to the South of France, Loch Ness, Paris, Cornwall etc etc with it.
We have 2 young kids, so don't exactly travel light! We get around 27Mpg when towing and 42Mpg solo (although it's the wife's car solo, and mine when we are towing
)
the only 'downside' is that the M-Sport required a removable tow-ball, and this limits the noseweight to 75KG (very difficult to achieve), rather than the (I believe) 90KG with the fixed BMW jobbie availabe on the SE. This had something to do with the body kit on the M-Sport apparently.
We are new to caravanning, and the car / van were bought new in Oct 2008. We have been on around 25 trips now (long and short) and have covered well in excess of 8,000 towing miles with no issues at all. That could be in part to the ATC fitted to our Bailey but probably also due to the excellent towing characteristics of the car itself. We went for the M-Sport specifically for it's stiffer suspension (which is self-levelling in the Touring). I suspect the stiffer sidewalls of the run-flats help too...
We easily keep up with traffic, and it's all too-easy to find the speed creeping up too much on long motorway stretches....
We are considering a new, larger, van for 2011 and will probably be forced to look at 4x4s for their greater weight but I can't fault the 5 Series at all.
HTH
Vince.