BMW gave me this to test out over the weekend (it's a 520d with M Sport Plus).
All in all I'm very impressed with it, such a low amount of road noise and a very smooth ride even with the M Sport suspension which I found to be a very good balance between comfort and sportiness. It can more than hold its own with the vast majority of traffic and whips up to 80 quite effortlessly. There were a few situations where I'd probably have liked the 30d, but I don't think I'd be too unhappy with a 20d, but as ever it'll depend on price differences. The figures they gave me for a 30d and 35d are very close, so I'd most likely go for the latter, if I went 3 litre.
Silver isn't my favourite colour, but it grew on me. I'd go for carbon black or mineral grey over it though.
The interior is great, though this one didn't have Pro Media, so the screen looks far too small. It didn't ruin the car like I thought it might, but it looks silly with so much plastic either side, the wider screen should really be standard (thankfully it's inexpensive). I'm not sure how I feel about the aluminium, it's nice but it's quite bright and there's a lot of it... I quite like that dark wood trim, assuming no piano black, or similar.
Definitely at the top of my list for my next car, it was pretty much what I expected and didn't disappoint. I'll have to try a 535d and see just how good it is.