Sudden deceleration

[Scubadude]

Was on a 45 mile drive on a highway doing 70 with advanced autopilot engaged. For three instances when I crossed under three different overpasses, the car suddenly dropped to 45 MPH. Scared the crap out of me. Out of nowhere, hard braking which lasted a few seconds. Thank goodness the cars following had enough distance to slow down.

I can only conjecture the electronics picked up the speed limit on the road I was crossing under. Very disconcerting. Anyone else experience this? I would think the car would recognize I was continuing forward, not making a sharp right turn out of nowhere to slow down.

 

[Zoomit]

very common...very unfortunately.

 

[Sophias_dad]

It is more likely that the AP was seeing the shadow cast by the overpasses than seeing the speed limit from the overpassing road. I'm sure its smart enough not to slam on the brakes because of a speed limit change, and also smart enough to know you didn't magically and instantly jump to the road crossing over.

But yeah, it happens. I've had it happen maybe three times in my 12k miles, but my AP roads are probably very different than yours, and I don't use AP all the time.

 

[kbecks13]

It's the radar return. Overhead signs/bridges can return some of the radar signals and the car momentarily freaks out to be super cautious.

 

[Mod3forMe]

Yes been there done that. Not fun.

 

[Scubadude]

very common...very unfortunately.[/Q

It is more likely that the AP was seeing the shadow cast by the overpasses than seeing the speed limit from the overpassing road. I'm sure its smart enough not to slam on the brakes because of a speed limit change, and also smart enough to know you didn't magically and instantly jump to the road crossing over.

But yeah, it happens. I've had it happen maybe three times in my 12k miles, but my AP roads are probably very different than yours, and I don't use AP all the time.

It's the radar return. Overhead signs/bridges can return some of the radar signals and the car momentarily freaks out to be super cautious.

Ahhhh, thank you. Only owned the car for one month. Slowly learning how it operates/handles in new situations.

 

[ewoodrick]

That's why I tend to keep my foot near the accelerator most of the time

 

[TaylorSFGuy]

I experienced a similar event during my 30 day AP trial. In my case, it seemed linked to roadwork that was completed some time ago unbeknownst to the GPS (exit 136 on North I-5 in Washington State). The AP wanted me to exit, make a right, then a U-turn and then another loop under the freeway before rejoining I-5 about where the non existent exit was thought to be. (The GPS still has this showing on the route). When I didn't let it take the non existent exit, the speed dropped and scared the heck out of me. I feel fortunate that no one rear ended me. This and a couple of other events has led me to decide that Autonomous Driving is not suited for my commute - I don't drive on freeways filled with sheep. Too much reliance on the car in front in my experience.

 

[rchung0]

It happened to me multiple times already. It happened this afternoon when I was on 105 driving at 70mph on AP. My 3 made a slight curve to the left, a car was on the next lane on the right ahead of me, my 3 suddenly braked. Must have sensed the car slightly ahead of me on the right lane. There was a Honda minivan following very close to me and luckily I quickly step on the pedal and the car accelerated quickly and avoided the Honda crashing into me. the driver behind me was cursing me with his hand gestures. I was thinking of putting a sign on my tail saying " Caution! Sudden deceleration due to Tesla's faulty AP. Stay far!" It is too unfortunate that this occurs so often. I really love the AP but this is driving me crazy.

 

[Grossie]

Don't you all remember the guy who was decapitated when he went under a white truck while watching a movie with AP on? I imagine this is to avoid those sort of situations that Tesla finds particularly uncomfortable! i don't think the guy felt anything, BTW, but I'm sure his family is not very happy.

I haven't had this happen yet, but I use AP mostly while traveling on a highway in traffic, rarely getting over about 20.