It's a tough one! In the case of the car you've linked, a 2015 reg, if you seen yourself keeping it for a good few years, then the potential loss when the majority of depreciation of similar cars has already occurred it wouldnt be as big an issue. Also, offset that against the savings you made initially. With a fairly desirable motor, when the potential buyer sees that you've owned it for so many years, proves that you had very few issues (or maybe not), despite it being a Cat D, that in reality its a good car!