I am thinking of getting the GC diesel. My only concern is the cost of the urea replacement. I understand it will have to be done every 3 months or so. If that is the case, it might cancel and MPG advantage the engine would have over the regular gas engine. Also read that the 8 speed auto will shave a full second from the 0-60 with the 3.6L engine. I will be in the market for either the diesel or the 5.7 with the 8 speed.