This will all depend on your options. The best method is go to the track and jump on the scale if they have one. My 87 curb weight is supposed to be 3325 but I have bare minimum options ( I don't even have power locks) and have taken out the spare tire/jack and the vanity mirrors bringing the curb weight down to 3150 w/o driver.
C4's generally are between 3200 and 3500+ depending on what year and car. The early C4's are the lightest (as evidenced by the postings in this thread) , some down in the low 3200 lb range full of all fluids and without a driver (totally stock). As the years went on more weight was added in more frame support , more equipment , bigger wheels tires and brakes, etc.
The latest C4's tend to weigh 3340-3380 depending on the options etc. My personal 96 LT-4 totally stock weighed 3340 lb full of all fluids and without me in it. My car is fully optioned .
ZR-1's usually range from 3450-3520 or so full of all fluids, no driver.
C5's are indeed lighter than our C4's with most loaded coupes being around 3225, most hardtops being 3175 and most Z06's 3115-3125 - again , full of all fluids , no driver.
All this is based on the numerous books I have read, magazine tests, and most importantly local track scales. Hope this helps....... :seeya