Stopping distance for collision avoidance System to activate

Try setting up some cardboard boxes and driving into them?

 

Your stopping distance is dependent on your speed and the speed of the object you're about to collide with. If you want to see what happens when the system engages, you can run into some cardboard boxes or watch people on YouTube run into cardboard boxes
https://video.search.yahoo.com/video/play;_ylt=A0SO8xBZZApYJ6oA2LJx.9w4;_ylu=X3oDMTEyMGlydDQ0BGNvbG8DZ3ExBHBvcwMxBHZ0aWQDQjI3NzdfMQRzZWMDc2M-?p=toyota+collision+avoidance+system+youtube&back=https%3A%2F%2Fsearch.yahoo.com%2Fsearch%3Fp%3Dtoyota%2Bcollision%2Bavoidance%2Bsystem%2Byoutube%26pvid%3DXdpEUDIwOC689XU9V59KjQUTNjYuOAAAAACRNTef%26ei%3DUTF-8&turl=http%3A%2F%2Fts4.mm.bing.net%2Fth%3Fid%3DOVP.Ve3c0e13659c52cd03bb529652c1a44f1%26pid%3D15.1&rurl=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DzAeEnLr3WYk&tit=Toyota+Integrated+Safety+-+Pre-collision+System+with+...&l=204&vid=70e784d392bffa3a7929d05ec3167301&sigr=11brubukb&sigb=14298jp5o&sigt=11o4pp571&sigi=12bprr7qu

 

if cardboard boxes don't work, tape aluminum foil to the boxes facing the car.

 

I don't think there is a single right answer. Many variables are taken into consideration and likely a bit of calculus to determine for a given instance when to initiate a panic stop. Then there are always the situations where the impediment to travel enters the danger zone to late to stop from the vehicle's current speed; and then yes, there's going to be a collision. Hopefully not quite as bad as it might have been without the collision avoidance system.

 

If it's RADAR, I'd be surprised if Cardboard Boxes are unlikely to work very well - maybe you'd need someone in the cardboard box.

Seriously, I'd trust TOYOTA - their testing methods are far more rigorous than anything you or I could do.

Or look here - from about 2:15:
Official Toyota Prius 2016 safety rating

 

It's unpredictable. The warning gets very sensitive when I'm accelerating and the car in front is decelerating. Tonight I was following a dump truck. It warned me twice as he was slowing. I was a long way back. So size seams to matter.

 

So far so good. I'm not going to tempt fate with this system.

 

The system is designed to help stop or minimize the severity of the collision. It does not guarantee you will completely avoid the accident. Speed, road traction and other factors all affect your stopping distance even when you do it manually. It is a whole lot better than running full speed into the obstacle in front of you. It is a safety feature that may save your life

 

I look at it as a safety feature. One that MIGHT step in for me if I accidentally miss a cue. It's like a safety belt for me. I always drive like I'm not wearing one. Given that, it did slowed down the car once for me radically when a car in front of me was turning off the road. I would have missed the car at my speed since it would have been gone by the time I got there. But now I know it works and I'll make sure to not get so close to turning vehicles. So in that case, it has made me a safer driver.

 

Alright, let's say it another way. You're asking a question that doesn't have an answer. It's like asking, "How fast does a Prius go on a freeway?" Depending on what Prius you're asking about, the answer is infinite. Specifically to your questing, depending on thousands of different variables, the answer is infinite.

 

I have the PCS turned off, but I suspect it's the same with "radar cruise control". Using cruise control, the system is VERY conservative. It slows the car when I wouldn't. I would be very surprised if any Prius actually ran into something with this system engaged. And mine is a GIII. I'm betting the G4 is better.