My product placement strategy for Cadillac has two categories: Mainstream, the B, C, D, and E models, and Niche, the S and X models. The S-Line is based off of the imaginary LWB Sigma II platform like my DTS. It has two vehicles - the SRX, a luxury tourer, and the STS (or STC), a four-door coupe.
Four-door coupes are becoming extremely popular. With the Mercedes-Benz CLS entering its second generation and the Audi A7 on its way, a bold new opportunity opens up for Cadillac. The Deville and Seville were sister cars (at least from my point of view)...the Seville/STS being the athletic car and the Deville/DHS/DTS being the comfortable car.
Case in point: The new STS. An athletic four-door with the attributes of a midsize-large car with the soul of an Eldorado. Base engine is a twin-turbocharged version of GM's direct-injected 3.6L V6. STS-H pairs the standard 3.6L with a hybrid powertrain. STS-V throws in a turbocharged 6.0L V8.