S Lines are a nice upgrade over standard, you just have to remember almost everything is an option! I had an 06 A4 S-line and it essentially added a more agressive front bumper, colour coded rear splitter, a slight lip on the boot, boot pop, lower suspension, nice steering wheel, metal or piano black trim, instead of wood, bettter alloys and nicer seats. Everything else was still an optional extra. That includes auto lights, electric seats and bose. For me it was closer to the difference between the old mondeo tit x and ST. Good car, loved mine to bits.