Just purchased our 2018 Yukon Xl with Lane Keep Assist. The lane keep assist will not turn the wheel until I am approx.. 18 inches over the lane. It will then move the steering wheel to get me back in. if I don’t touch the wheel it will go all the way over the opposite side lane approx. 18 inches and when the vehicle crosses the lane line on the opposite side it advises to take control of the vehicle and vibrates my seat on the side I’m over that line. I was informed by my GMC dealer this is normal and they took the vehicle for 2 20 mile test drives. I asked them to put in writing that 18 inches over the line is correct according to GM engineer that they had on the phone. Every ounce of my body is telling me this is not how it was designed. On a back rode in New England you are lucky if a pole or tree is off the road by 18 inches. Which means before Yukon even senses I’m over the line I would have hit something. I had a 2015 Yukon with Lane Departure Warning and the thing would go off if I was within 6 inches of the lane on either side. Someone Help!!!!