Audi Buyer's Guide
The S badged vehicle line belongs to AUDIs performance enhanced cars, the manufacturer offers S models in almost all of its models. All of these so called S vehicles come with upgraded brakes, suspensions, spoilering, sportier interiors, and high performance engines and unmatched performance. Similarly to the BMW M cars and the Mercedes AMG models there is only a few parts that are interchangeable with their regular corresponding models.
S cars like the above mentioned manufacturers vehicles are on the top of their model line, and tend to hold their resale value better than the regular models, since most of the time their not an upgraded version and that itself would help used resale value, but produced in lower numbers making them not as widely available.
AUDI offers all of its models as an S line vehicle not to be confused with a real S car, these vehicles are in general wearing the true S or similar spoilering, but don't have the high end engines installed in them, in europe they generally call these as optical tuning