It has been well established by the Blackwing engineers why the 4 has a V6 not a V8, and it wasn't the "MBA types" that made the decision.
Yeah, we've heard the "it earned it's place" and the V8 wont fit. And it's better for weight distribution. (But is a 4 cam, twin turbo V6 really any lighter than an NA pushrod V8?) And I'm sure when the Blackwing team had to turn the 4 into the BW the die was already cast and a V8 was never going to fit.
However, when the ATS was turned into the CT4, they could have easily left room for the V8. The product planners gave the engineers a list of requirements and in my imagination the exchange went like this:
Management to engineer: "here is your design specification for the CT4:
1. Production cost at 10,000 vehicles / year shall be $20k/vehicle
2. NRE budget is 50 cents (so don't change too much from the ATS or you'll never hit your budget)
3. Don't make the back seats big enough to fit adults or no one will pay more for the CT5 (we product planners call that "differentiation")
4. Performance targets X, Y, Z
5. Must fit LFA engine
6. Base CT4s must use 2 liter 4 cylinder truck motor
etc."
Engineer to management: "I'm not sure a 4 cylinder truck motor is the right fit for a Cadillac. You know, the Camaro and the ATS share all their hardpoints. If we put the Camaro engine bay on this thing, we could fit all the V8 engines GM has spent billions of dollars designing and building factories to produce. Unlike 4cyl truck motors, the V8s are awesome - people love them - I mean people get tattoos of GM small blocks - not so much with 4cyl truck motors. Offer the 4 cylinder as the base motor, but the V8 as an upgrade. (Remember what Iacocca did in 1964?) All those young people that bought a Camaro (or Mustang) and have kids and need 4 doors for their next vehicle, they could step up from a Camaro/Mustang to a CT4 with a V8 instead of buying one of those $55,000 SUVs that sell like gangbusters. Sure, it would be smaller than an SUV, but the V8 would be a huge differentiator in this sigment and lots of people that would have bought an SUV would buy the CT4 just to get the V8. And don't worry about the CAFE impact - buyers will totally pay more to cover the CAFE penalties - look at what Dodge is doing - their CAFE rating has to be 12 mpg - they put the HEMI in everything. And the GM pushrod smallblock is like half the size of the humongous HEMI. Plus we could do a V series version and it would be...."
Management to engineer: "Cadillac is a premium product. Cadillac customers expect a 4 cam motor. Why do you think we spent $50M designing that 4 cam, hot V, twin-turbo blackwing motor? Oh wait, nevermind... Your job is to execute the design specification given to you by the product planners. If you want to be a product planner, go get an MBA like me. I don't want to hear anymore about this. Understood?"
Engineer to management: "Yes, sir."