I'm not sure that anyone is going to have "exact" numbers for you as it applies to V6 Camaros. But if you think it over yourself, I'd bet that you can come up with some of the answers on your own.
Here, I'll ask you a few questions.
Where in the structure of a car do you think you'd have to increase strength as you increase horsepower?
Imagine all of the systems affected.
Now ask yourself how much of that you would engineer twice so that you could offer both high and low power versions of the car.
That's where the weight is.
Most of it resides in the structural members of the car (unibody/subframes...), but it also affects every other mechanical system in the car.
So, the V6 Camaro has much beefier components than it would if only the V6 were to be offered.
The car had to be designed to meet the maximum powerplant, so it is overengineered and reinforced for lesser drivetrains.
In the case of Camaro, weight reduction was one of the design parameters - so this car is no overweight pig that could have been a featherweight. The Camaro team was constantly badgered about this exact issue all through development once the Camaro crowd learned that it was to be built on Zeta.
If they could make money marketing a "stripper" a few more pounds could come off, the same goes for easier safety regulations, or they could have saved a bit of weight by using a live rear axle rather than IRS.
But that's about it.
The only other solutions are raising the price quite a bit by using expensive lightweight materials in more places, or shrinking the car to a smaller platform.
Still, with only an 8% differnece in weight vs. Genesis, would it be worth it?
The Genesis itself is not offered with a V8. Are you sure that it has been engineered for one?
Concepts don't count here, and I'm just asking, not claiming to know.
I can tell you this for certain though. If Genesis is engineered (as produced) for a V8, then it weighs more than it needs to. And, if it ever gets one, it will weigh quite a bit more than the few pounds added by the larger engine because other components will need to be augmented.
I'm not trying to fight you here,BV.