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
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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.
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.
