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.

 

[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.

 

[Gus75]

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 have tested this many times and it never brakes even when your 6 inches away from car in front. I have had many such experiences in my cx-5 2021.5 Signature model. See my question on auto reverse braking also.

 

[RedBaron]

Then take your car to the dealer and have them check.

 

[Gus75]

Then take your car to the dealer and have them check.

3 year Warranty over

 

[GrampaSlade]

it did it one time to me when I was already yawing left to go around the car. I didn't touch the brakes because apparently, I'm smarter than the computer and know what's going on. The guy behind me was probably wondering what the idiot (me) was doing. Color me not impressed

 

[chickdr]

The only time it ever happened in my car was on the interstate in heavy traffic. Cars stopped suddenly in front of me and the system activated. Worked well other than the Jetta behind me which had to swerve and move to the break down lane to the side of me to avoid hitting me. The other annoying thing was after the event, my infotainment system locked up and would not operate until the car was turned off and back on again.

 

[RedBaron]

3 year Warranty over

SO, you'll have to pay. What's the point of asking this in multiple threads if you're not going to get it fixed?

 

[Gus75]

SO, you'll have to pay. What's the point of asking this in multiple threads if you're not going to get it fixed?

My reply was to the person who advised, I take it to dealer to get it checked out. I was not going to pay dealer now
. Quote" 3 year Warranty over"..

 

[DoubleCH]

I have tested this many times and it never brakes even when your 6 inches away from car in front. I have had many such experiences in my cx-5 2021.5 Signature model. See my question on auto reverse braking also.

Were you totally off the brake pedal? I think if you are even slightly on the brake pedal it won't brake for you. The best way to test is to follow a car finishing a curb-lane turn at intersection where u know it would definitely clear your lane by the time you are at its spot, all the while you keep your city speed and don't lift or brake. This is the situation where people complain the emergency auto brake triggers.

 

[hsdejong]

I do not recommend testing the Mazda Smart Brake Support on the road in real traffic.
Just test it with a light cardboard box in a safe place.
Put a blanket over the box to make sure you do not damage the car paint.

 

[DoubleCH]

Please note that I said "it would DEFINITELY clear your lane". This is actually the common annoying situation where people complain the turning car would definitely clear the lane by the time their car would be anywhere near it.

 

[hsdejong]

Gus75 complains that the car never brakes automatically. He doubts whether the system works. That's why I think there's no point in testing this in traffic.
And what if the car brakes really hard and his car is rear ended?

He says he'll go to the dealer to have it checked. That's the most sensible thing to do.