Indeed, DPF stands for diesel particulate filter. The particulate emissions of diesel engines have been the subject of numerous recent discussions in Germany and it is expected that forthcoming changes in German car tax will favour cars with very low emissions of this type. It seems that the Germans are becoming very reluctant to buy diesels without DPF's and there are predictions that the residuals of diesel cars without DPF's will suffer in a bad way.
VAG were quite late with the introduction of DPF's and had to do it in considerable haste. The 'new' 2.0TDI DPF-equipped engine in the A3's is in fact a bored-out version of the old 8-valve 1.9TDI engine and so, in a certain sense, is a step backward from the much more modern 16-valve one. It is not certain when (and if) the current 16-valve engine will be equipped with a DPF. It is likely that in the future the 16-valve design will be used just in the forthcoming 170PS 2.0TDI engine with pieso injectors, while the current 16-valve 140PS engine will be dropped and replaced by the older but cheaper to manufacture 8-valve DPF-equipped design.
The demand for DPF-equipped A3's (available from the 2006 model year) in Germany and Austria is obviously so high, that Audi seem to have decided not to offer these cars in the UK.
