The spinning is dictated almost entirely by the weight distribution of the riders and not by anything that Disney can adjust. I've been on some rides where it's spun a lot, others where it didn't spin much at all. It's simply the weight distribution and where the heaviest point of the car is located when it hits a curve. If the heaviest point is already pointing toward the curve, it won't spin much. But if the heaviest point is turned to the side as it hits the curve, it'll be flung into a spin.
I suppose that Disney *could* fool with the spinning (knowingly or unknowingly) by adjusting how well-greased axles and bearings are, or installing some kind of brake restrictor on the chassis, but I've never heard of such things being done.
-Rob