Derivation of S4 Name

[drobbins@net2net.com (David Robbins)]

I know that the current Audi product names x3/x4/x6/x8 are determined by the
size of the vehicle in the product line, but were did the original 100-based
S4 derive its name from.  Was it the fourth "Sport Quattro" (preceded by the
original Sport Quattro, the S2?  Was there a/What was the S3?

-DMR.