Yeah, all 170's are DPF.
Don't be sucked in by the marketing on economy though. There is bound to be a post up here about what other A3 owners are ACTUALLY getting with their fuel consumption. I mean, my combined figure is meant to be 53.3 mpg, but if you look at my sig here, I'm only getting 37.2 mpg. And that was taking it really easy, with a couple long runs. The last tank was only 34.5, and before that 33.2. To me, with the way I was driving, they are petrol figures, not diesel.
Especially compared with the mpg I had on an extended test drive in a BMW 520d, where the ACTUAL mpg was 47.9, on a run absolutely similar to the ones where I'm lucky to get 35 in the Audi.
Before you put any money down, try to arrange an extended test drive first. I took that BMW out for a couple hours, and did about 140 miles, across motorway and country A-roads, as they are the roads I regularly drive. Then got a realistic figure from that run (I reset everything before I left, and drove as if I owned the car). I just wish I had done this before forking out on the Audi.
That said, there is no better looking, similar motor on the market than the Audi, so if you can live with the poor economy, it is a nice car to own.