B Mode

[moggio53]

This may sound a bit daft, but here goes. My wife just puts the car in D, and off she potters. I always use B since I believe this provides regen and the electric motors slow the car down and not the brakes - who's right and does it really matter

[MikeSh]

20 minutes ago, moggio53 said:

since I believe this provides regen and the electric motors slow the car down and not the brakes

Why don't you don't think this happens in D.

(Since Toyota built these for 'average' people then wouldn't they make regen the most obvious and easily selected option?)

[Mojo1010]

B mode is for engine braking design to use when descending a steep hill. D is driving. 

[CPN]

45 minutes ago, moggio53 said:

This may sound a bit daft, but here goes. My wife just puts the car in D, and off she potters. I always use B since I believe this provides regen and the electric motors slow the car down and not the brakes - who's right and does it really matter

She's right and you are wrong. "B" is to provide additional engine braking when you are descending a steep and long hill.

Also, her MPG figures will be better than yours since driving constantly in "B" mode will use more fuel.

[moggio53]

2 minutes ago, CPN said:

She's right and you are wrong. "B" is to provide additional engine braking when you are descending a steep and long hill.

Also, her MPG figures will be better than yours since driving constantly in "B" mode will use more fuel.

Thanks guys - thats cleared that one up!!

[Cyker]

It's a bit weird as the B-mode behaviour has changed slightly in the different generations of HSD (Hybrid Synergy Drive, the 'official' name of the Toyota hybrid system).

The older ones *would* go maximum-regen in B-mode, as well as engine-brake, which could under certain circumstances return better mpg, and is partly why this incorrect 'fact' of B-mode being for regen keeps getting repeated by a lot of ignorant car journalists (The same ones that think it has a belts and cones gearbox  ).

However, the newer HSDs like in the Yaris, Corolla and probably RAV4 do fairly minimal regen, in both D and B-mode, when you lift off the accelerator - one block (out of 3) of regen shown on the power. This is theoretically better for economy as you can coast a lot further when lifting off, and the only way to get the max regen is by using the brake pedal - That lets you get up to the full 3 blocks of regen.

I'm not sure why they changed the behaviour in the newer HSDs, as it made sense to me to max-regen in B-mode, but now it stays at the same level of regen as D-mode, and instead dumps the rest of the energy by acting as a very inefficient air-pump with some fairly aggressive engine braking.

The B-mode is actually quite pointless though - It's designed to save your brakes on e.g. a long descent, but if you just use the brake pedal, it'll hardly use the brakes and instead use maximum regen and charge up the Battery, but when the battery's full and you continue to brake, it switches to engine braking anyway!

 

[TonyHSD]

I don’t think the older ones go full regenerative braking in B.
Gen 3 for example when in B and going downhill and lift off the accelerator the regen goes down just a bit and if the downhill is steep you have to use the brakes otherwise the car will start gaining speed again. 
The cruise control can use so much more regen braking than B mode. I am often using the CC when going downhill and I am watching it on the dashboard the power meter hand can go halfway where in B mode only 1/4 max. 
D is the only mode for driving and B only in ultra rare occasions.