I test drove a cts on water covered asphalt and over a type of tarp with water on it. It did not kick in at all on the wet tarp, but on the road the car hooked. To me, electonically, wheel spin is wheel spin. Does anyone have an answer for this?

 

Sounds like the programming is maintaining an estimate of stiction and won't apply any brake or throttle inputs below a threshold. This is what I was taught to do when recovering from a skid over icy conditions so it would make sense.

 

am i correct in thinking that stabilitytrac, abs, and traction control/limited slip are all different... and that you are actually referring to traction control?

 

The car is likely calibrated to allow some wheelspin on very low mu surfaces. Otherwise, the traction control system will end up reducing the effective delivered torque to a near-zero value, with the result of no forward progress.

Traction control systems with lesser sophistication that intervine only via methods of reducing engine output are notorious for taking away too much power on very slippery surfaces. Avoiding this problem goes a long way towards increasing customer satisfaction.