Depends how completely new the model is - if it's all new I like to wait 5 years - but often the platform and powertrains are simply carried over into a completely new body so a couple is all I wait.

The 2015 focus due out this year isn't a new model really, it's just a facelift of the existing model.

Prices are likely to be a bit lower 12 months on as well

To be honest, there are probably as many examples of manufacturers getting cars right-first-time as there are 'lemons.'

The problem is that ancillary components (like DPFs and their sensors, or fuel injectors) are expensive and can have a disproportionate effect on a models' reliability - for example the recent case with Mercedes diesel Bluemotion cars and the dodgy batch of injectors, which caused supply problems.