Is EV really that useful? Also, is B fine to always use?

Shift early, and you get mild compression and a moderately straining engine for a long distance. Shift late, and you get strong compression with a screaming engine at 4500+ rpm, though for a shorter distance.

I prefer the lesser noise & stress.

 

This is quite easy on GenIII, and a good way to modulate B-mode drag to achieve any desired level between normal B-mode and normal D-mode.

 

Interesting info here, thanks

About a week ago I had the chance, for the first time, to try out B mode (was going
down from a hill). When I engaged B mode, I was surprised by the rather loud noise coming from the engine (A bit like whining, and pitch dependent on speed).
Actually it surprised me enough to cause me to shift back to D.

Has anyone else encountered this?

 

They are.
I use B at the top of a steep hill when I know my battery will be full at the bottom even if I dump a heap of energy. This means I have regen longer and don't use friction brakes as soon.

 

Being correct makes him say that.

 

Certainly. This is what engine braking does; it pumps air through the engine to waste energy. The more engine braking the faster the engine has to spin. It really takes off and whines if you ask it to do a lot of braking.

This leads to one of the more counter intuitive things that you may experience in your Prius. Imagine heading down a long mountain descent, so you reach over and shift into B mode and take your foot off of the gas. Engine braking begins and you can hear the engine whining like a small turbojet. To the uninitiated, it sounds like the engine is working very hard to push the car downhill. It isn't; it is actually acting as a brake without burning fuel. You now decide that you need to speed up just a bit, so you press on the gas. The engine slows down! This is the counter intuitive part: pressing on the gas makes the engine slow down.

In B mode, when you press the accelerator pedal, you tell the Prius to use less engine braking. Less engine braking means spinning the engine less, so the engine speed slows. It's exactly the opposite of what you normally expect when you press the accelerator.

If you keep pressing harder, engine braking continues to drop off, eventually stopping. At this point you are coasting. If you press even harder, the engine will come on again, but now it will be burning gas and providing power.

If you get a chance, try this. It's really quite cool.

Tom

 

Yup. Non-hybrids do this too, if you downshift far enough in a manual transmission. But with the typically larger engines, the noise is usually less obvious.

This was a surprise the first time I saw it. But it took only a few moments to figure out what was happening, and put it to good use.