Clubjazz - Honda Jazz & HR-V Forums
Honda Jazz Forums => Honda Jazz Mk4 2020 - => Topic started by: nikolakisxy on June 15, 2025, 05:05:33 PM
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Hi to all. I've been recommended to drive my new 2025 Jazz, in town, using the position B on the shifter to save fuel. I have done so all last week and as amazing as it sounds it has halfed the consumption over driving in D. Any comments welcome. Thanks.
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https://clubjazz.org/forum/index.php?topic=14961.0
https://clubjazz.org/forum/index.php?topic=16169.0
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Correct me if I'm wrong, but theoretically I think that using B mode is the same as pressing brake pedal gently while using D mode. In both cases the Jazz brakes using the electric motor and puts the recovered energy into the HV battery. Only when the speed is slow, around walking pace, the disc brakes engage. Or if you brake so hard that the HV battery can not receive all that braking power (maybe around 30 kW).
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I use B unless I want cruise control. The effect on fuel consumption must depend on road conditions and your style of driving. It might avoid some mechanical braking.
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OK But assuming a similar pattern of driving in town, I've experienced an outstanding fuel economy using the shifter in position B. Thinking in terms of I. C. E engines it feels unnatural to use more power to overcome friction but the car is using electricity and not petrol. So far so good!
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B mode does increase the extent to which regenerative braking is used to slow the car, which is used to charge the the battery rather than being wasted making the brake discs hot. Great in theory .
I seldom use B mode,. I find on the open road ,in D mode ,the car maintains its speed with only the lightest possible touch on the throttle .Nice and 'perky'. In B mode the car will slow down quite noticeably unless you use more throttle than would be needed in D mode. Often fuel consumption is similar in either mode . The extra throttle needed in B mode negates any advantage it has from more regenerative charging.
Those who always use B mode may not realise just how much more throttle they are using. You get used to how the car 'feels'. But you will notice the difference if, as you can , you change between B and D modes while on the move. Maybe it doesnt matter ,if you are happy with the results.
City traffic is another matter . Fuel saving can depend on HOW you drive (sorry if this may insult some of you :-[ )
I try to slow down gradually well in advance as soon as I see stopped traffic, a red light etc ahead Sometimes I barely need to brake at all , even in D mode. . I doubt my fuel consumption would be much less in B mode.
But many drivers in city traffic drive up to stopped traffic at speed and only brake ,quite hard, at the last moment. We all do this to some extent, but may not realise it. I sometimes revert to 'city style' braking pattern if I have an impatient driver 'up my tailpipe' who apparently fails to understand why I am slowing so early and gradually. :P Also they might not notice I am slowing faster than them unless I show brake lights. Not shown with regenerative braking, with even more retardation in B mode.
I think my car is a bit more prone to getting rusty brake discs because I am so light on the brakes. Habitually using B mode may make this worse.
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Thanks for your prompt reply and comments. All points taken!
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The difference in B or D is akin to motorcycle engine breaking as far as I'm concerned. Nifty 2 strokes just carried on regardless when the throttle dropped, 4 strokes dropping the throttle was like applying a brake.
I use B mode around town, on twisty country roads, and switch to D mode on long open stretches especially motorways and when I want to use ACC.
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Agreed. I think it's the best way to drive the current Jazz.
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B mode does increase the extent to which regenerative braking is used to slow the car, which is used to charge the the battery rather than being wasted making the brake discs hot. Great
But many drivers in city traffic drive up to stopped traffic at speed and only brake ,quite hard, at the last moment. We all do this to some extent, but may not realise it.
Speak for yourself sonny! ;D :-*
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I have owned hybrids for over 10 years and have never used B mode apart from going down very steep hills so I get a bit of engine braking
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... and I've never used D :)
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... and I've never used D :)
So you have willingly deprived yourself from the comforts of ACC?
To each his own :)
I often switch to B in dense city traffic as it makes the ride more comfortable (less actually using the brakes).
Otherwise I prefer D as cruise control is only available in this mode.
On longer travels ACC and the lane keep assistant have proven quite a boon (for me).
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I have owned hybrids for over 10 years and have never used B mode apart from going down very steep hills so I get a bit of engine braking
That's what Toyota recommend for the use of B
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I have owned hybrids for over 10 years and have never used B mode apart from going down very steep hills so I get a bit of engine braking
Given the very limited battery capacity of our Jazz the recovery effect is limited as well.
Once the HV-battery is charged to its limit the Jazz shifts to a kind of noisy "retarder" mode where it turns over the "dead" ICE at sometimes quite high revs just to "burn" the surplus electrical energy from the generator.
Actually, it's a quite clever system - yet I do wish Honda would have opted for a somewhat larger battery.
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... and I've never used D :)
So you have willingly deprived yourself from the comforts of ACC?
To each his own :)
I often switch to B in dense city traffic as it makes the ride more comfortable (less actually using the brakes).
Otherwise I prefer D as cruise control is only available in this mode.
On longer travels ACC and the lane keep assistant have proven quite a boon (for me).
I've tried ACC a few times and as already posted, it failed, unnecessary braking when overtaking and I now use LIM in average speed zones
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I’m with Kremmen on this one, I use B mode 99% of the time but I sometimes use D (ACC) on motorways or long stretches of dual carriageways, I don’t like the sudden braking if your overtaking or when someone pulls across into your lane abruptly, and I’m using the distance setting of one bar - I find the system is to intrusive and prefer conventional cruise control which my SR is not equipped with.
:D ;D
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I've tried ACC a few times and as already posted, it failed, unnecessary braking when overtaking and I now use LIM in average speed zones
I've noticed this behaviour on my test drive in 2023 with a pre-facelift Jazz as well: It is quite annoying!.
My (Honda) MY24 Jazz has never done this; Honda must have made some improvements with the facelift.
Agreed, ACC has its limits but on the facelift seems to do a better job than on the original MK4s.
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I've tried ACC a few times and as already posted, it failed, unnecessary braking when overtaking and I now use LIM in average speed zones
I've noticed this behaviour on my test drive in 2023 with a pre-facelift Jazz as well: It is quite annoying!.
My (Honda) MY24 Jazz has never done this; Honda must have made some improvements with the facelift.
Agreed, ACC has its limits but on the facelift seems to do a better job than on the original MK4s.
Mine seems ok. I use it on a once a week journey, 22 miles on motorway plagued by lorries and slip roads, but I find the ACC works fine. I tend to sit behind something doing around 60, and let the system do what it does. If someone enters from the left, I just boot the throttle and move to the outside lane.. then back in again and the system reactivates. On the occasions that some prat has missed his exit and cuts in, the ACC does brake.. but nothing excessive or sharp really. It never seems unpredictable or causes me concern.
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I use B simply because the car responds more like one with a conventional internal combustion engine.
I'm not that bothered about petrol economy, given the mileage I drive.
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I just use D in eco mode as i dont use the ACC . Even on a motorway i like to drive Jazz but then i dont drive hundreds of miles in one go . The tech is very clever and noticeable that quite a few german cars with prices the wrong side of £40k have ACC as an option …! 🤕 ouch