CADILLAC STS V8
The STS is what you'd call Cadillac's midsize luxury sedan. At the smaller end, the CTS is shockingly good. In CTS-V format, that car even makes The Good 12 v2.0. Up above the STS in terms of size sits the DTS, a front-wheel drive luxo-barge meant for older citizens of southern Florida. In between you'll find three varieties of the STS, only one of which finds itself in The Bad 8 v2.0.
What's wrong with the V8? Well, nothing actually. The Northstar engine was one of GM's conquering moments... of the 90s. Since that point, General Motors' excellent 3.6L V6 has come along. So has the supercharged Northstar. That leaves the STS V8 just 18 horsepower up on an otherwise nearly identical car that costs $9,500 less. Sure, some options on the V6 may be standard, but essentially, this V8 is a lame duck that Cadillac has forgotten to kill.
If you really need more than the V6's 302 horsepower, you could try out the 469-horsepower STS-V. One way or another, the STS V8 is not a happy medium.
Alternatives: Cadillac STS V6, Cadillac CTS-V, Audi A6, BMW 5-Series
Necessary Incentivizing Required To Switch To The Good 12 v2.0: Considering the STS V6's lack of Good 12 placement, who knows? Certainly, pricing in line with the V6 version would help.
Anything Else? General Motors can build luxury cars, the Cadillac SRX; Escalade; and CTS to name three. Don't hold the STS V8's pricing scheme against GM.