Stopped at an intersection behind a bus today at a red light. Decided to look for some new music so I turned Autopilot on, seeing as how I couldn't see the red/green light and that'd tell me when to pay attention (car starts moving... don't tell me you guys never use it for this, either!). Was at a complete stop about two car lengths from the bus. Engaged AP. Car immediately lurched forward. Hit brakes fast, which fortunately my foot was already over the pedal as I'd been previously stopped. Sat for a second confused. I'm now about a car length from the bus. Verified my AP was set to 4 car lengths. Engaged again. Car immediately shot forward, hit brakes. Car displayed the warning that an object was in front of me. Took out my phone to take a picture and the light had turned green by that point, so it looks like the bus is further away than it was (you'll see the green traffic light in the distance and cars already in the intersection). I'm wondering if a combination of the color of the bus (sky blue) plus the fact that it had a graphic of a car on it "tricked" AP into thinking this wasn't a bus in my way maybe? If you look at the bottom of the photo you'll see that the AP screen shows a car, not a large truck/bus, and that it's offset left... just like the graphic is on the bus. I am pretty confident that either the car would have emergency braked or I would have hit the bus had I left it engaged. It definitely pulled forward full-power like it does if the person in front of you changes lanes and the lane is otherwise clear. It definitely made me think of all those people who accidentally drove into buildings and such and the little reaction time they must have had to figure out what was going on. EDIT: Refreshed Model S running 8.0.