the "B" gear

You can use "B", but it is less efficient as you lose some regeneration. I've been driving a Prius for over 6 years now and have never used the "B" except once to see what it did. However, I would use it going down a long steep hill.

 

You're wasting energy/gas. B mode will do some engine braking, which throws energy away, some of which you can capture with regenerative braking. Engine braking is mostly useful for slowing down when your battery is already full enough... ie on long downhills in the mountains. I haven't needed it yet. But, no, you're not asking for trouble, just lowering your mileage. (in the case of the freeway stop... the downhill depends on how big a downhill you're talking about)

 

Most of the time, the Prius is using just regenerative braking when stopping, until it gets below 7 mph. Then the friction brakes take over. So if you are stopping smoothly, and not abruptly, your friction brakes should last well over 100,000 miles, as they are doing very light work.

When you really need to stop quickly, the friction brakes will apply. And if you are in a real hurry (stepping on pedal quickly and forcefully), the Brake Assist function kicks in, which can almost put you through the windshield if you don't have your seat belts fastened.

If you train yourself to look ahead, and not just at the cars immediately in front of you, you should be able to stay in regenerative braking for the majority of your braking (subject, of course, to the 7 mph cutout).

I only use "B" mode for long hills.


Best wishes,

 

i tend to like to use B too when i'm on the freeway. in D there is almost a delay to braking... since i was in an accident a few weeks ago, i wanted the quicker slowdown time.. i feel since B starts the slowdown as i let off the gas, my stopping distance is shorter.. it may be a pain to the people with automatics behind me as I'm almost emulating a manual... but... there is a comfort factor behind it.

 

Around Seattle, use "B" for Stevens Pass, and possibly portions of Snoqualmie Pass (and other mountain roads) if experience shows that you would be filling the traction battery on the downhills. Otherwise, is just reduces MPG.

The battery current limit restricts regenerative braking to moderate braking force at street speed and very light braking force at highway speed. Heavier braking will always bring in the friction pads. To maximize energy recovery, long light braking will do better than short heavy braking, IF you have the space available. In a surprise freeway slowdown, you don't have enough space for this.

 

Both of those situations could usually be handled with regenerative braking alone. I'd say if you've got time to think it and go to "B" then you've probably got time to brake on regen (or at least mostly regen) anyway.

I sometimes use "B" if I'm decending a large enough pass that I know I'll reach 8 green bars well before the bottom of the decent, but that's the only time for me.

Thinking about V8Cobrakid's idea of using "B" all the time for freeway driving, it's probably not that bad an idea. If you're always over 42MPH then the ICE will be always turning in either case, so I don't think it would cost anything in FE to do that. The only reason I wouldn't do it is because I know I'd probably forget to switch back and be driving inefficiently after leaving the freeway.

 

"B" does not light the brake lights. Getting rear-ended can ruin your whole day.

 

"B" is equivalent to a single downshift on a normal non-hybrid transmission, a common and accepted practice that also does not light the brake lights.

 

People get rear-ended that way also :_> We want our speed changes to be more visible, not less.

 

Every time I've been in a car that was rear-ended (at least 4 times), the brake lights were on, with the car completely stopped at a stop sign or red light.

Or if the brake lights were not on, the impact jolted them back into operation before we could discover any failure.

 

The bright red lights make for a better target.

Tom

 

Hello Richard:

I have to agree with Fuzzy1 that the analogy of likening the use of B mode to slow down is akin to downshifting on a manual transmission.

There is no law stating that one can only slow down using a method (e.g., friction brakes) that activates the stoplights. At least not that I'm aware of.

So I can empathize with those who want to use B-mode to slow their vehicle. Although I don't use B-mode for this purpose myself, if I rent a vehicle that has a manual override on an automatic transmission (such as sport-type paddle shifters on the steering wheel, tap-shifters, etc) I'll use the transmission to slow the car when approaching a stop.

For those of us who grew up on manual transmissions, this is a very "natural" way to drive.

Best wishes,

Frank

 

No doubt it's legal everywhere, it's just a little less safe and wastes a little more fuel. Have fun :_>

 

If you are concerned apply light pressure to the brake pedal as you select B. If people kept a safe following distance this would never be an issue. I doubt B would slow a Prius so quickly that a driver who is awake and following would not be able to avoid rear ending the Prius, I'd be more inclined to blame the driver of the following car rather than the lack of bright red lights on the rear of the Prius.

I also can't see there being much speed differential between the vehicles if the following car was too close to react before impact. That is provided the driver of the following vehicle is even slightly awake.