There's basically 3 types of weight on the car; static dead weight, unsprung weight, and rotational weight. The best type to reduce is unsprung rotational as that not only reduces a small amount of dead weight, it more importantly reduces the critical spinning weight that affects the handling and delivery of power to the wheels.
Unsprung is any weight not supported by the springs, such as the wheels, brake rotors, etc. I've read various estimates of the benefits but reducing unsprung rotational weight is about roughly a 10-1 ratio of benefit; reducing 1 lb of unsprung rotational has the same effect on performance that reducing 10 lbs of dead weight does.
So rather than spend thousands on carbon fiber body panels that might reduce 20 lbs of dead weight, spend those thousands on lighter brake rotors, lighter wheels, lighter clutch/flywheel, lighter driveshaft. Most of that isn't visible compared to a CF body panel but boy will you feel the difference.
Here is a link to my build thread where I've documented my quest to reduce weight on my 2010 SS without removing seats, sound insulation, gutting it, etc. The interior is stock.
http://www.camaro5.com/forums/showth...t=45165&page=2
The gross vehicle weight right now with a full tank of gas is about 3,685 lbs. All the numbers and mods with several dyno sheets showing the results of various mods are in the thread. A lot of it would be useful info for you and you get the added benefit of knowing that what I've listed works, without you having to do the research.
I'd be real interested to see what a ZL1 would do with about 100 lbs of unsprung rotational weight removed.
