VW Golf GTi 1.8 Turbo
This was swapped with the BMW 525i Sport - but what a disappointing car this was.
It was unexpectedly noisy on the motorway, it was difficult to have a normal conversation!
And we had quite a few problems with it too, although nothing serious I suppose.
We were happy to see the back of it.
Update Nov 2016
Having checked the MOT history of this car online, it appears to have been a good car for it's new (or current) owner, having passed previous MOTs with no issue. Perhaps we resolved all the issues during our ownership.. :P