THE term ‘sports diesel’ has slipped into the automotive lexicon without much fanfare. However, only few manufacturers have been brave enough to sell such a car, given that most of the market would think it a contradiction in terms. Yet opinions can change – many traditional petrol car buyers who once thought a diesel did its best work in a truck or large SUV are beginning to view a diesel car as not such a bad thing. The question is: can the RS TDI be sufficiently sporty when it counts for an owner who wants fun out in their mid-size family car.