CX-5 Auto Braking

[Pitter]

Today I came up fast on a stopped vehicle and I think I had my first auto braking experience. There were three warning beeps and I felt the brakes activate (I think) but I hit the brakes myself at about the same time. My impression was that I was awfully close when the auto braking kicked in and I wonder if auto braking really would have stopped me from hitting the car in front had I not interfered with my own braking.

 

[murky]

Today I came up fast on a stopped vehicle and I think I had my first auto braking experience. There were three warning beeps and I felt the brakes activate (I think) but I hit the brakes myself at about the same time. My impression was that I was awfully close when the auto braking kicked in and I wonder if auto braking really would have stopped me from hitting the car in front had I not interfered with my own braking.

I'm confused. You essentially hit the brakes at the same time that auto braking engaged. You didn't hit the car. That sounds about just right.

Did the antilock kick in? I imagine the safety braking waits until it needs to be very aggressive and then engages hard.

 

[chickdr]

I can tell you in my '21 it worked when I was in a tight situation on a packed freeway. The car in front of stopped short and auto braking stopped me immediately.

 

[181962]

I wonder if auto braking really would have stopped me from hitting the car in front had I not interfered with my own braking.

I'm quite confident in saying, "it depends".

In my 2020 there are four automatic braking functions (I'd hesitate to call them discrete systems) that might come into play--Smart Brake Support, Smart City Brake Support, Advanced Smart City Brake Support or the Stop and Go function associated with radar cruise. You can get some idea of when one or the other might be engaged by reading the manual.

In each case the manual offers the same cautions--the vehicle may not stop in time. These assists should be viewed as better than nothing when they engage when they should. They are potentially problematic if they engage when they shouldn't as some have reported though I have not personally had that experience.

There are some extreme cases where I'd be certain these functions would not save you such as if you were tailgating and the guy in front slammed on his brakes. There is a line somewhere among the less extreme cases.

 

[HeloJoe]

In each case the manual offers the same cautions--the vehicle may not stop in time. These assists should be viewed as better than nothing when they engage when they should.

This is the key point. These emergency systems are designed primarily to reduce your speed prior to a collision. Better to rear end someone going 35 mph instead of 65 mph. If they happen to stop you completely, great, but a manufacturer isn't going to claim that outcome, especially if higher speeds are a factor.

I can say with relative confidence that if the system is set to high sensitivity, and you're traveling at low speeds (think like ~30 mph or lower), you'll stop prior to a collision. I find that Mazda's system is very heavy on the brakes in cruise control.

 

[181962]

I can say with relative confidence that if the system is set to high sensitivity, and you're traveling at low speeds (think like ~30 mph or lower), you'll stop prior to a collision.

It seems to me there are three factors: the speed you are traveling, the speed or rate of deceleration of the vehicle in front, and the following distance. If you're tailgating at 30 mph and the guy in front slams on his brakes I doubt these functions would prevent a collision.

Edit: I overlooked an obvious 4th. factor--road conditions. Slick roads causing longer stopping distances would increase the likelihood of a collision in many circumstances.

 

[Pitter]

Thank you, excellent replies.

 

[erhayes]

What I don't like is my CX5 2022 is still braking after the vehicle in front has made the right turn. Release response is often too slow IMO. Ed

 

[wlong01]

What I don't like is my CX5 2022 is still braking after the vehicle in front has made the right turn. Release response is often too slow IMO. Ed

Yep, same thing in our 19.

 

[chickdr]

The two posts above are my biggest gripe with auto braking. I don't seem to have this issue in my CX-5 (neither my 19 GT or 21 GTR have done it with cars turning in front of me) but my 16 Acura RDX would scare the crap out of me at times by starting to activate (loud beep and warning on the center display) when I was nowhere close to the car in front of me. It seems to me the systems need a little more work to perfect the operation.