Having owned a ZQ8 equipped Chevy in the past I don't believe you can actually tow with it despite it having a two rating. The Xtreme has some sort of tow rating and I did pull a couple trailers with it but GM flat out told owners to not tow anything. When I questioned why it had a trailer hitch, and a fairly beefy one at that, the dealer told me it was to hold the rear bumper on...which was entirely true.
The non-ZQ8 Colorado with the V8 has a tow rating of 6,000lbs so it could pull a car, but add the ZQ8 in there and I have no idea how it works out. The rear springs on the non-ZQ8 are 2,900lbs too so I'm guessing it would be even less with ZQ8 installed.
