When talking about Cadillac STS, we should firstly know its predecessor, Cadillac Seville, because STS is the abbreviation of Seville Touring Sedan, in other words, Cadillac STS can be considered as one variant of Cadillac Seville. The first Cadillac Seville was released in 1975 as 1976 model year, total four generation Cadillac Seville cars were released in 28 years. In 2004, Cadillac Seville was replaced by Cadillac STS, which was the flagship sedan in Cadillac lineup.