Clubjazz - Honda Jazz & HR-V Forums
Honda Jazz Forums => Honda Jazz Mk4 2020 - => Topic started by: CB72 on March 12, 2025, 07:30:44 PM
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Has anyone had any experience with the collision mitigation braking system, just interested in how good it is. It not something I fancy trying it out myself, maybe find a large cardboard box to drive at ;D
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I had my HR-V temporarily apply the brakes when it spotted a cyclist (who wasn't on the road) on a potential collision course. The cyclist turned a corner to take a parallel route and the brakes were quickly released.
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Just once ,soon after I bought my 2021 car .A Bus had stopped at a bus stop. I was hemmed into my lane by a 'keep left' Island but the bus was stopped far enough beyond that Island that I could maintain my approach speed , fully intending to safely pull out and overtake once clear of the island.
The system, being 'unaware' of my imminent intention to steer , applied the brakes. Not hard, as my speed and the detected distance to the bus were still fairly reasonable. It ceased as soon as I demonstrated I was in control of the car by steering. (or braking) . It think it would braked harder if the perceived danger was more imminent and serious.
It did disturb me a bit at the time. I didnt lose control or anything but a driver following me could have been taken by surprise by my car unexpectedly braking for no obvious reason.
I reduced the detection distance slightly (and perhaps subconsciously modified my driving) and have had no further incidents.
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From 2:27 in the Euro NCAP video shows you the different scenarios of CMBS (or AEB as they call it)
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The system can operate very abruptly if the barrier of a parking garage does not open properly.
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had it applying the brakes only once.
That saved me from a collision, it happened at the approach to a roundabout where I assumed the car in front of me would go ahead and I was looking to approaching cars already on the roundabout coming towards me.
But the car in front stopped and the system instantly braked full force, and stopped with 1 mm left between cars.
Speed was about 10 kmh so that also helped to avoid a hit.
On multiple other occasions I have the orange rectangle flashing and sometimes also beeping,
usually in the same corner near home on a 50 kmh road with a tight left bend and cars parked on the side.
Similar to LV's experience the car does not know that I will go left to follow the bend, and starts warning.
After 17000 km this is the only "assist" system I really appreciate, all the others are 'not finished products'.
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I have it regularly on motorways. I generally use the cruise control, sitting around the 65 mark. Sometimes I catch up with something slower, and it will kick in and gradually slow me down to whatever the target vehicle is doing. I honestly don't mind, and I know just kicking the throttle will negate it and let me pass... if I can be bothered. Sometimes I quite like dropping down to 60, leaving a nice gap...let the system work. I'm never in a hurry.
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Never had CMBS go off :)
Had a friend with a 10G Civic and he had a regular trigger and slowdown as the road he lived on had a bend with a tree on an outside corner
Just like an above post the system thought was going to go straight on and hit the tree instead of going round the bend - which he did frequently on that corner :)
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Out of interest, what braking or warning system(s) does the MK4 have? The MK3 has two systems which can be easily confused:
Forward Collision Warning, which is the one that gives false alarms as you close up for an overtake, or when you go round a corner and there's an oncoming car. This does not apply the brakes, just warns you.
City Brake Active, which only works at very low speed and does apply the brakes if it detects that you're about to hit something.
Does the MK4 have these as separate systems and which one is the OP asking about?
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ColinB, Mk4 has both of those systems, but in the user manual they are both included under the same term, which is Collision Mitigation Braking System (CMBS).
Also I think that in Mk4 it works at high speeds as well, because sometimes, although rarely, when I'm driving 60 mph on motorway, it suddenly starts braking, after seeing some bright red illuminated signposts, which I guess it thought were tail lights of another car. Or maybe it was not the CMBS. Maybe it was the Adaptive Cruise Control. I'm not sure.
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I tried the ACC very early on and IMO it's a complete disaster unless you are the only car on the road or just following one vehicle
Any overtaking move was almost impossible as it identified the vehicle in the left lane as though it was in my lane and slowed me down. Understandable if I was pulling out at the last minute but I'd pulled out well ahead. It only sped up if I went to the extreme right of my lane and then got me back up the set speed like I was on a racetrack
To make sure I stayed at my set speed during overtake and didn't exceed the speed limit I switched to the LIM function
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I think in my 2019 Crosstar it only works with cruise control?
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When I said my CMBS has only activated once I really mean its has only reached stage 2 once, where it brakes gently. It has probably reached stage 1 a few times where it displays an amber warning light, and sometimes a buzzer. TBH I tend to ignore a flashed orange warning light to some extent ,and especially white warning lights ,apart from quickly double checking I am indeed fully alert and in control. :-[ Not yet had a stage 3 'collision unavoidable,' brakes forcefully applied. :)
The adaptive cruise control with' low speed follow ' uses similar detection technology, and frequently activates as part of its normal function of detecting the proximity of other vehicles. But its not quite the same thing. The manual specifically warns that ACC has limited braking capability .
All cars have CMBS . It activates at speeds above 5kph/3 mph when it detects pedestrians , cyclists and other solid obstructions where there is a speed differential of 5 kph and a risk of collision.
At speeds above 30 kph/18 mph it also detects frontal oncoming vehicles, and oncoming vehicles when you make a turn that crosses an oncoming traffic flow . (This appears to be altered between Right hand drive and left hand drive cars to favour whichever side of the road is normal - presumably when I drive my Right hand drive car on the continent it doesnt give quite the same level of protection for left turns across traffic.)
It also says it detects oncoming and stationary vehicles at speeds up to 100 KPH/62 mph . Unless I have misunderstood, its another way of saying it doesnt detect things if you are driving above this speed. Its understandable it cannot detect with accuracy at the speed and distances involved - and of course its above the speed limit for A roads anyway in the UK . The manual also lists several pages of situations where the system may not detect things, ormight detct things it should not. Such as on bends etc..
CMBS doesnt claim to be able to fully stop in time, just to mitigate the speed of a collision. Its a drivers aid not yet a self driving car :P