Rented is yesterday - what is "B" ?

Hi. The "B" position on the shifter is the Prius version of downshifting. It will slow you on a downhill without using the brakes. The Prius uses electric and the engine to get to and maintain the speed you want. It will shut down the engine when you slow down or brake. Enjoy, Jerry

 

Zack, the why's of the engine and electric motors will make your head spin. After a few days it will make more sense. In stop-and-go traffic the main battery will drop to 2 or 3 bars and panic most people. It does what it needs to do at the time, but a low main battery will give less acceleration till the Prius decides to charge it up. It will make sense in the end. Enjoy, Jerry

 

It's a secret "Budget" mode, hence the "B". It allows the employees to drive the cars without activating the unnecessary cost control restraints that silently communicate via satellite to corporate headquarters.

Most Budget employees thought the "B" stood for Backwards, and couldn't find a hidden switch with both hands, so they had to put it in plain sight on the shifter.
Same employees thought the "R" stood for "Race" and you can understand the rear end damage that caused.

Any more questions?

ZC1

 

All joking aside, Congratulations on picking the Prius.
It's a great choice and after driving one, you might even want to buy one.
Try to see how much gas mileage you can get by letting off the throttle during declines and coasting to red lights.
It's a fun car.

ZC1

 

Running more on electric only would reduce the gas mileage and increase overall emissions, which is contrary to why you would want a Prius.

Tom

 

"B" should only be used when coming down long hills or mountains, to avoid riding the brake pedal. If you use "B" in ordinary city or highway driving it won't damage anything but it will reduce fuel economy.

 

Is there an advantage to driving in "B" in heavy stop and go traffic? I ask because I have a 2006 Ford Escape Hybrid. I am strongly considering purchasing a Prius to replace it or one of my other vehicles and am spending a good amount of time here to learn more about the car. I am renting a Prius this weekend to play with since no one has one to test drive. Driving the FEH in low, which sounds like the substantial equivalent of "B", in rush hour stop and go traffic improves its mileage in my experience. The additional regenerative braking also makes that type of traffic easier to deal with. Many of the FEH hypermilers (of which I am not) actually drive in low a significant amount of time while city driving in congested areas.

 

"B" does not equal Low Gear. It equals compression braking which is wasteful compared to regenerative braking.

 

You're getting a little mis-information. "B" mode is the equivalent of "low" or "1" selection on an ordianry automatic tranny car. Which provides a form of "compression" braking by the engine. It's for going down steep grades for long periods like driving down mountain roads. It has no real practical use other than that, and will reduce overall gas mileage.

The Prius will run extensively on "electric only" and do something even better we call "gliding", which is running on nothing but kinetic energy. You gotta lean how to manipulate the Hybrid system in the car. It's all done with the gas pedal and energy screen.
The gas pedal has more function than the gas pedal in an ordinary car.
When folks learn (realize) that, they can begin to exploit what this car is really capapble of.
Or, they can lazily do what they always done and get mediocre (by Prius stds) mileage.

 

Sorry, but now I'm still confused and would genuinely appreciate being straightened out. The FEH also has a CVT. By putting the FEH in low, the regenerative braking strategy changes such that it feels very similar to engine compression braking, but it is not. When in low, taking one's foot off the gas causes the braking system to kick in more quickly and more firmly, again feeling similar to engine compression braking. This is actually quite helpful in stop and go traffic where you can't leave significantly long distances between you and the vehicle in front of you. Is this similar or no?

 

No, not really similar, except in the sense that both involve engine braking. The Prius does not have a CVT in any conventional sense of the word. The Prius has a fixed ratio planetary gearbox with is always engaged. Said another way, there is no shifting, downshifting, low gears, or clutches. The effective gear ratio is changed by varying the fields on the two motor-generators. By sending more or less power through the electrical pathway the effective gear ratio is changed.

In B mode, the Prius spins the engine via the electric motor to waste power. You want to do this on long downhills where the battery will become fully charged, otherwise the friction brakes are going to work harder, possibly overheat, and wear out sooner. That's the only reason to use B mode (there are some special technical reasons relating to traction control, but that's beyound the scope of normal driving, and not relevent to this discussion).

Tom

 

I'll be the first to admit that I don't know much about the FEH, but are you sure about this Tom?

This sounds an awful lot like my understanding of the FEH. Am I mistaken? How does the FEH combine the ICE and MG?

Again, I thought the "L" setting on the FEH behaved like this as well. Am I mistaken?

Here is where I think there might be a difference between the FEH and the Prius. From the limited amount I've read about hypermiling the FEH over at CleanMPG, I think the FEH might alter the decision on stopping the ICE when driving, gliding, or coasting in "L" vs. in "D" at speeds below 41 MPH, whereas the Prius seems to be rather consistent in that decision regardless of "D" or "B" setting.

Lacking any expertise with the FEH, I'm reluctant to post any specific descriptions of how the Prius differs from the FEH.

 

Using "B" in the Prius will slow you down a lot faster than simply coasting in "D", but it will also reduce fuel economy. The only time "B" should be used is to avoid the possibility of overheating the brakes, and the only time that can happen is when you're coming down a long steep hill, not in normal driving. There is no place in Florida that needs "B".

If you just hate to keep tapping the brake pedal in stop-and-go traffic you certainly can use "B" instead, but MPGs will go down.

 

You are talking about the Ford Escape Hybrid? I misunderstood when you said CVT, since the Escape lacks a CVT. The hybrid system on the Ford is a clone of Toyota's HSD, with older battery technology and Ford's control algorithms. Changing gears in the Escape only changes the control parameters, just like with the Prius. As for changing when and how long the ICE runs, I don't know. They could easily do that, but I have no experience with it.

Sorry for the mix up.

Tom