[David]

Cost is what I recall being the biggest issue on the GMC trucks.

We have it on our Panamera. I have mixed emotions about it. In a parking lot it's great. On a tight twisty road near the limit it does help. On the highway just cruising at a decent clip I'm not a fan since to me it feels weird. I want a car to feel rock solid at high speed with all steering on the front end and not have the rear end try to help the steering.