At that price point you could be buying more of a liability than an asset, so you'll need to shop carefully. There's not much difference in economy between the petrol six and the V8 despite the superior performance of the V8. The consensus however is that the six is cheaper to run and more trouble free. If you go for a six with the manual 'box (five speed up to 2004, six speed thereafter) you'll also bypass the problem of the auto box failure.