What to buy?

[jeremyp]

I am looking for a bit of advice here and I am going round and round in circles. I have done 30,000 miles in my 2000 A8 2.8 Sport in the last 10 months (and another 2,000 in my Z4 in that time!). It's now at 102,000 miles and I know it will go on for much more but it's starting to make noises and if I am honest I have decided that it will start to fall apart soon.
In March, I need to get out of my Z4 - I do too many miles for it to work for me and it costs many many hundreds of pounds a month and right now it just sits on my drive. So, in March, I was thinking of giving it back to BMW (I am not a big fan of selling privately) and I will probably need to give them about £4K to get out of the finance (ouch!). I was thinking I would trade in the Z4, the A8 (they may give me £2K for it) and then buying a second hand BMW. This was looking like a 2007 7 series (with about 25k miles), then it was a 2005 X5 (with about 50k miles) and then it was a 2007 6 series (with about 50k miles). I was looking to buy a car for about £20K and HPing it over 5 years to keep the monthlies low (I don't have £20K sitting around!).
However, I then thought about the D3. I absolutely love the comfort the D2 gives me - it is the most relaxing drive I have ever had. I don't need a fast sports car (I am building one of those). So I was thinking, maybe spend £10K on a D3. It will have pretty much have all the kit I want and be an improvement on the D2 (which is good anyway).
Obviously I will have to lose all my ICE that is in the D2 but that is not too much of an issue a long as I can get the ipod playing in the D3. And I am a bit concerned that I won't have bluetooth in the D3 - am I correct in that thinking? (I think £10K buys me an early one? 2003ish).
Also, do I have to worry about lots of electrical niggles like MMI breaking?

So what does anyone think? I need a large comfortable car that I can pile miles on (about 35,000 a year) and not worry about it devaluing too much (because it's not massively expensive in the first place or it has a low starting mileage)