3600 lbs sounds like a decent estimate. I personally think the v8 camaro will come in a bit heavier, I'm guessing a tad under 3700 lbs.
And on a side note, the ATS V is shaping up to be a mighty fine car, and the GT3 spec race car is looking pretty nasty.
http://www.racer.com/pwc/item/108174...677703821217_n