S Line models were pretty much end of line models introduced in 2005. They had the best spec of the lot by all accounts and the model was carried over to the B7 models that came out in 2006 on a 55 plate.
The S-Line models added 18in wheels, stiffer sports suspension, s-line leather steering wheel, s-line badges on the rear flanks and usually leather or half-leather interior.
Of the two models posted they both look nice. 1.8T models are the lightest, quite tuneable, and are quite punchy and fast but can suffer problems, particularly with oil pick-up pipes and sludge usually brought about by servicing with the wrong oil. Coilpacks and boost issues can also occur, but there are plenty of these about with big mileages on them so they can last well if properly looked after.
The 2.4 engine will be smoother and probably sound nicer but doesn't necessarily offer superior performance. High tax band (CO2 emissions) and heavy fuel economy are downsides too.
The 2.5 TDi is a swift and smooth performer though and is well worth a look. The V6 TDi engine is smooth and responsive and is easily tuned too. Not the cheapest thing to service (cambelt services can be expensive) and the tax band isn't the cheapest for a diesel, but if serviced properly these will do astronomic mileages.
Which ever one you go for they are a lot of car for £5.5k.
Good luck,
J
