On the back of my car it has the symbols 2.0T and the "T" is red in color. But I've seen other Audi's the just have a silver "T". Im pretty sure I dont have a S-Line so I was just curious if it represented something.

 

You must have a 2006 (like me). They changed it to a silver T for 2007.

 

All I have ever seen on the red "T" had to do with equipment and year of the A4. Models in Germany had them up to 2007, and they had some type of sports package. Also they had the stationwagon with the optional 220hp engine, so that had the red T as well. For the US version's it had to do with the equipment package, not the horsepower up to 2006. Afterwards I think it was on some, but not all S-Line models. Why? Maybe the Audi assembly folks had to get rid of the red T's!