I'd have got a bigger car but we were getting to the point where we couldn't get it in the garage (no drive).
Had been driving a 207 hatchback, very happy with it, just wanted more boot space partly for the dog but mainly so I could get my bike in/out more easily. Narrow local lanes + quarry lorries made me nervous of rear mounted bike racks and I decided I'd rather change the car then spend out the money required on roof mount.
Didn't think I wanted a huge estate so started looking at smaller estates, Golf sort of size, but the 2008 felt tiny in the drivers seat compared to my 207, test drove an A4 and found that weirdly small in drivers seat too. Golf also seemed poor value for money compared to the Passat.
So somehow I ended up at the bigger end of the spectrum, thankfully not a problem just hadn't been my initial preference, was still on the verge of walking out of the Audi dealership to go talk to VW about a Passat when someone suggested sitting in an A6. Somehow the money for a new one wasn't any worse than the 6 month old A4 Avant I test drove and it felt much better to sit in. And a black one was already built and on it's way to the UK... might have chosen a dark red otherwise!
I'm still not really sure how I went from wanting a bit of a bigger boot with a budget similar to Crackle's to getting a brand new A6 but I'm not complaining!