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The "B" Gear

Discussion in 'Gen 2 Prius Main Forum' started by DanCole42, Apr 21, 2005.

  1. DanCole42

    DanCole42 New Member

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    The manual doesn't make it clear, so I'll ask around. What exactly is the "B" on the gear selector for? I know when I use it, the car slows down considerably. Does this improve the regen braking? Does it affect gas mileage? In what sorts of instances do people use it?

    Thanks!

    -Dan
    AIM: TheEmperorOfRome
     
  2. Frank Hudon

    Frank Hudon Senior Member

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    do a search on B Gear and read up. Thousands of lines have been devoted to it.
     
  3. richard schumacher

    richard schumacher shortbus driver

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    It's to avoid riding the brakes when going down a long hill, equivalent to putting an old-style transmission in 2nd gear. It mostly reduces fuel economy so avoid using it otherwise (not living near mountains, I've never used it).
     
  4. NuShrike

    NuShrike Active Member

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    I use so I don't ride my brakes down a long hill, coming off the freeway, or when I need that extra stopping power as part of emergency braking.

    Just like S-mode on my Civic cvt.
     
  5. spknicks

    spknicks New Member

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    Use Engine Braking as often as you can! It is like putting your old automatic trans into a lower gear, use it like you would use a manual trans down shift, such as slowing down before stopping. [font=Arial:58e09c3489]Now here is the best part "Engine Braking" sends kinetic energy to run the electric motor and what is not needed to run the electric motor is stored for future use!!![/font:58e09c3489]
     
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Hey there spknicks. Careful though. That'll only work at 35km/h and lower (using the generator). Any speed higher than that and it's use the engine itself to slow you down and that's just wasted energy as the pistons pump up and down.
     
  7. spknicks

    spknicks New Member

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    yep, you are correct! thanks (I knew that! lol)

    along that same vein, slower stops and slower starts does the same thing, uses kinetic energy to run the electric motor and stores the extra in the batt. (less gas engine running = more MPG)
     
  8. gschoen

    gschoen Member

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    B Mode will make absolutely no difference in emergency stopping distance. Emergency stops use good old regular, reliable friction brakes.

    Riding your brakes on the Prius won't cause brake fade, unless you're pressing down hard enough for friction brakes (regen braking doesn't heat brake pads) or your battery is completely charged and won't accept any more juice.

    You won't get any more regen using B mode than using your brakes. There will be more regen when you lift your foot from the pedal, but you can get the same level of regen still with the brake. You will get lower MPG since your engine will be spinning more, and coasting is far preferable to regen for MPG.

    There are very few instances B mode is needed for safety. It certainly doesn't offer any MPG improvements, usually it's for novelty or driver comfort (traffic, less pedal switching, etc.)