If you bothered to click on the Car And Driver link, you would have seen that these systems (particularly Tesla's system) work at least up to 50mph with stationary objects.
In the video, that’s 50kph (30 mph). The most advanced Volvo system decelerated but still crashes pretty hard at 80kph (50mph) when approaching a stationary vehicle decoy.
Note well, if the target was an inflatable rock or an inflatable jersey barrier parallel with the direction of travel, the results would be much, much worse.
In those other cars the ACC is picking up a car-like object on the sensors. A non-car-like object is designed to be ignored.
I read the C&D article when it came out last year. Pretty sure it was linked from HN actually. They ran some tests with a few cars driving into inflatable vehicle decoys. As I recall they found the systems would fail as often as not.
I was speaking in terms of this crash, which was not a primary collision with another vehicle, when I said that AEB will not activate for stationary objects at speed.
The ACC will activate for a stationary vehicle at speed, but will not save you entirely at even modest speed. At 70mph even ACC can drive right into a stationary vehicle.
These systems often work by sharing the ACC sensors and lock onto and track vehicles. This is why C&D discusses specifically the case of a lead vehicle swerving to reveal a stopped vehicle, and how some systems fail to acquire the stopped vehicle in time to provide any brake input at all;
> Volvo's owner's manuals outline a target-switching problem for adaptive cruise control (ACC), the convenience feature that relies on the same sensors as AEB.
(C&D did not test drive a Volvo for that test, but they did review the Volvo system and comment on it)
It would not be fair to take the C&D testing with inflatable vehicle decoys, and use that to claim Tesla is behind by not activating AEB into a narrow profile partial forward obstruction (parallel jersey barrier).
Partial forward obstruction of a non-car object is the absolute worst case for false positives, because this roughly translates into “any signal at all on the forward sensor”.
I’ll try to find sample images of what the sensor data looks like under normal operating conditions and when looking at narrow profile forward obstructions.
This is a very tricky edge case. A bird can fly in front of you. Water can splash up from the car in front of you. An empty trash bag floating up in the air after being run over by a car in front of you.
I did not mean to imply ACC or even AEB will not slow down a car heading for a rear end collision with another stopped car. I was speaking about this event specifically. I apologize for not being more clear in my 1 sentence original reply.
