Would the traction control mechanism not make a difference in gas mileage? I mean, the engine is still producing the same amount of power, it really depends on how the traction control works. I would think that it's just some kind of dampener in the transmission that reduces torque output. In which case the engine would still be using the same amount of gasoline, the transmission would just diffuse the power along the powertrain. I don't know how the traction control system works on the Crossfire, but that's all I can think of. Another option is that it lightly applies the brakes. Does anyone know actually how the traction control prevents wheel spin?

But yes, with traction control on you'll get better tread-life, and A/C takes a huge hit in performance and economy. I seriously doubt that ESP has any impact on gas mileage.