this is probably very obvious to many of you... I am liking the B mode and use it a lot to slow down. in my small-er home town, this was no problem as the traffic was never that much and people generally drove less aggressively. today on a dual carriageway leaving a big city,, I was on the fast lane following the traffic flow but everyone was going at below speed limit, like 70kph. (-_-!) behind me a civic was tailgating me. out of nowhere a dead stop traffic wave hit us. I see the brake light of the car in front; I shift to B, which was not enough, so I hit the brake then I realized it's still not enough, I had to depress the brake all the way down. my tires were screaming for a good half a second. while I avoided the truck ahead, the civic hit my derriere. surprisingly both cars were fine, because judging by the impact I felt, I was convinced there would be at least some dent. after the incident I switched to the slow lane and realized, I should just avoid using the B mode in such heavy traffic all together. 1 it is slower to shift to B than to use the brake pedal, and 2 with brake pedal the civic would see immediately my brake light and start to slow down as well. Of course the civic shouldn't tailgate, but my new found habit was equally bad. and I could also leave some more space between the truck ahead. this is probably lame for many of you, i just want to write it down like some self examination, whatever
Besides the traffic hazard, it is also a slightly wasteful energy practice. Some of the potential energy recovery of regenerative braking is thrown away as engine compression braking. My first Prius was also hit in a similar highway traffic situation, but not for the same reason. Gradually slowing traffic, just enough to light up everyone's brake lights, turned into a sudden stop, with no change of brake lights. I stopped fine, as did the guy behind me. But the teenager behind him, with a car full of other teenagers, didn't notice in time and caused a three car chain reaction. My spouse was momentarily in a panic that our relatively new car was very seriously damaged, but it turned out to be only the a nose imprint of the middle car on the rear bumper cover.
B mode depends how you use. I used it without any issue or incident/accident. The civic tailgating you should be fxxx. Those civic, getter ..guys are always think we Toyota drivers are slow, stupid and tailgating to give us pressure which is disgusting. Those guys should be blamed.
B mode is fine for long steep descents, but is a fuel waster above 24 MPH. And yes, since there are no brake lights, it is dangerous in traffic.
Why the fuel waste? AFAIK in "B" mode the ICE acts as compressor - is the gas still delivered to the manifold or the electromagnetic valve close the fuel flow?
If you were NOT in B, you would store more energy via regeneration, so you would have more stored energy and not use fuel. Toyota is not storing the compressed air to power the car later.
Pity I meant.. when the ICE is operating during "B" mode some would say that it consumes the gas - which I don't think so.
It doesn't burn gas at that moment...however it wastes energy that could be captured with regenerative braking for later use.
a) if you can shift gears in your Prius, I am eager to hear about it. b) in a manual transmission, if you slow without brake lights, sure.
I have used {B} mode to get people off my butt in heavy traffic. Imagine their surprise when the car in front of them drops speed, rapidly, with no taillights. They have no choice but to suddenly hit their brakes. Then, just when they come back up on my butt, it happens again causing them to hit their brakes again. "Clearly," they think, "this guy has no taillights. I better drop back." The most I've had to use it on one person was three times. They all drop back eventually. Stupid? Probably. Dangerous? Potentially. Entertaining? Usually.
Use your brakes. That why you have them. "B" is just for reducing some of your speed on a descent and is a waste of energy when used as you have described.
Rookie mistake, but hope you learned from it! Glad your prius was not damaged. Sometimes in our enthusiasm to try to squeeze the most out of the Prius, or to save gas we do dangerous things. I am guilty sometimes as well, but I am trying to minimize my obsession to sometimes squeeze the most out of a gallon of gas.
IMHO the only time it makes any sense to use B Mode is when the battery is completely charged and you need to slow down, such as descending a long steep hill. Actually even under those conditions you don't need B Mode. You can still use the brakes in the regenerate portion of the HSI and if the battery is full it will automatically use the ICE as an air pump (just as if you had selected B with the shifter) to help you slow the car.
Some hills still do need B Mode. Yes, D mode will perform as you describe, but produces weaker compression braking than B, too weak for numerous hills. (Even B is too weak in some places). B mode also allows the driver to begin compression braking before the battery is full, useful on long hills where the battery will fill up anyway and the driver's ears would like to reduce the amount of that high rpm jet engine roar.
