Auto lane change question

[milleron]

My Model S is brand new. The first time I tried to use Auto Lane Change, she started to move into an occupied lane. My hands were on the wheel, so no disaster occurred, but I was shocked. I presumed that the AP-2 hardware and software would assure that there was no car adjacent to mine or overtaking it in the adjacent lane before starting to steer into it. Was this a malfunction, or is it completely up to the driver to make sure that it's safe to change lanes?

 

[BrettS]

The car does use the ultrasonic sensors to try to determine if the lane is occupied before attempting to switch lanes. However, they are very short range (maybe 5-8 feet at best) and not 100% reliable. You should definitely make sure that the lane is clear before letting the car switch lanes, however it will prevent or abort a lane change if it does detect a car there. It will likely not detect a car overtaking you at all, but should detect a car next to you before you actually hit it, at least.

At some point as AP2 evolves and they enable more of the cameras it should have better detection skills.

In general it’s best to think of autopilot as cruise control on steriods... it can help take some of the burden of driving the car from you, but you still need to be paying attention and making sure the vehicle is operating in a safe manner. Look before changing lanes, keep your hands on the wheel and your eyes on the road.

 

[Troy]

Neither AP1 or AP2 have rear radars to detect a car approaching from behind on the lane you are about to change to. AP2 has rear cameras but those have only 100 meters rear visibility according to this diagram released by Tesla. Mercedes uses 200 meter rear radars (source) but even that is not enough which is why they don't do auto lane change either. At least 400-meter radars are needed but the technology is not there yet.

Therefore instead of trying to attempt to detect bullet cars approaching from behind on the target lane, Tesla has done something different and very clever. They gave up on that idea but instead focused on detecting cars behind you that are a safe distance away and traveling at a similar speed. It is a very clever system in a sneaky way. What this means is, if there happens to be a car behind you on the target lane a safe distance away traveling about the same speed as you, AP2 can now be sure there is no bullet car approaching from behind. Even if there was, it would not hit you but instead, it would hit the car behind you on the target lane that is being detected.

In other words, AP2 will do "automatically change lanes without requiring driver input" like Tesla says in the Design Studio here but it will only do that if there is another car behind you on the target lane, a safe distance away and traveling at a similar speed to you. Elon described this feature as "maneuvering around other cars" (source). See my messages #95, #97, #112 here for more details.

Some people might describe this as misleading or overly optimistic advertising. I agree. Unfortunately, this is one of those issues Tesla doesn't seem to be able to fix. They can't help themselves but exaggerate.

 

[milleron]

In other words, AP2 will do "automatically change lanes without requiring driver input" like Tesla says in the Design Studio here but it will only do that if there is another car behind you on the target lane, a safe distance away and traveling at a similar speed to you. Elon described this feature as "maneuvering around other cars" (source). See my messages #95, #97, #112 here for more details.

Some people might describe this as misleading or overly optimistic advertising. I agree. Unfortunately, this is one of those issues Tesla doesn't seem to be able to fix. They can't help themselves but exaggerate.

Thanks. After these explanations, I think I'll regard Auto Lane Change as merely a way to change lanes without disengaging AP. I'll continue to check for blind-spot neighbors and rapidly-overtaking cars as a

That's quite a shame, because the blind-spot warning on my old Fusion Hybrid, with nothing but ultrasonic sensors, worked so perfectly and reliably that I came to trust it with my life -- if I could see nothing in the outside rearview AND the BS warning was not illuminated, I knew it was safe to change lanes without breaking my neck to visually check the blind spot. I expected my 2017 Tesla with its AP2 hardware to be even better. It really hurts to realize that it's not even up to the standards of 5-yr-old Fords. In fact, for all practical purposes, it doesn't even have blind spot info at all. (Those evanescent, dim, hard-to-see, inaccurate white arcs around the car image are essentially worthless to me.)
What a massive disappointment. Knowing that my Model S has the same sensor array as decade-old conventional cars but that Tesla cannot be bothered to implement them in a life-saving way, seriously weakens my faith in the company.