Went to test drive the new BMW Z4 yesterday and it was a really nice drive, and I honestly came so close to buying it. I'd pay £4k up front and only be paying about a tenner more than I pay for my Audi TT.
One of the big things holding me back is £3-4k negative equity on my Audi if I trade it in, but the BMW garage did bring up a possibility I hadnt considered before, Voluntary Termination. By my calculations I've paid over 50% of the total finance including the balloon payment so I would be able to. My biggest worry though is how that might impact my credit file. Everything I look up online says that finance companies will mark the agreement with a VT market rather than settled, and whilst that SHOULDN'T cause any issues with future finance, it's not a guarantee and there's always the possibility of it being flagged up. So I'm strongly leaning towards just waiting for another year until the finance is over so I can hand the Audi back worry free.
The other drawback is that it is a petrol rather than Diesel engine, which is a concern on a 150 mile round trip to work, but when I was driving the Z4 it seemed to be getting about 45-50mpg at 70mph which is only about 5 less than my current Diesel engine.