I am a HUGE autopilot fan and engage autopilot every chance I can get on the highway. There are some limitations however that have made for some uneasy behavior which causes me to take over (even though there is no warning given from the dash): I find most of these instances occur when there is an 18 wheeler in the next lane slightly ahead of me on the passenger side (right lane for me). I'm not sure the range of the autopilot sensor, but it probably is the length of an 18 wheeler because if the driver sort of drifts near the lane markers, I have noticed that my autopilot markings completely disappear on that side. And rather than use the remaining driver's side lane to guide it, the car all of a sudden acts a bit crazy and actually goes toward the truck as if it is trying to visualize the right lane markings). I try to gently nudge the steering wheel to correct it but on more than a few occasions the vehicle fights me and it feels like we have a sinusoidal course because of it (a bit unnerving for the passenger I had at the time as well). This has happened on both normal sunny conditions but more prone to happen in the rain. I am curious if that has happened to anyone else. This also occurs if a truck is ahead of me and then changes to go back into the slow lane (i.e. as the truck crosses the lane markers to get to next lane, sometimes autopilot goes crazy). I am curious if that situation has happened to others or if this is abnormal and I should get it checked out.