Driving mode “B” on Prius 2007

This has got to be one of the coolest features of Prius, and certainly one that saves you gas and brake pads, but it has to be used with some caution. It makes the car behave differently from what the driver of a car behind you expects and might cause some issued.

“B” is for “braking with the engine” and what it does is this: turns the electrical motor connected to the wheels into a generator. So, if you are going down the hill you can put it in “B” (can switch back and forth between “B” and “D” – normal driving – at any time) and that would provide enough resistance that the car would decelerate without you actually touching the brakes.

You can continue driving in “B” mode if you don’t feel like switching it back but the cur is going to feel underpowered really bad and your power consumption will suffer. The way I understand the feature is: the gasoline motor would still provide enough power to drive the car forward should you decide to drive in “B” mode and get your batteries charged really quick but this is not what it’s been designed for.

So, let’s get back to what it was designed for: to provide a temporary additional charge to the battery while slowing you down. The thing is: the deceleration is minor but you can feel it and the driver behind you is going to be really confused because you are clearly decelerating at a rate that would correspond with slightly touching the brakes in your regular car but your stop lights would not come on! This is a bit of a hazard issue the way I see it because I personally tend to use this feature all the time. And I can just see how it gets on the nerves of the driver behind me because he or she just can’t understand what’s going on even though they instinctively feel that something is not right. Everybody seems to be accustomed to a particular rate of deceleration when you would have simply let go on the gas pedal and in this case Prius would decelerate just as your regular car. “B” mode is different although stop signals do not indicate that.

Another thing to consider is this: the electrical motor turns into a generator every time you depress the gas pedal. The “B” mode makes the charging controller take more current to charge the batteries a little quicker than they would when you just decelerate with the rate that looks like you are just coasting in a regular car with automatic transmission.

4 Responses to “Driving mode “B” on Prius 2007”

  1. Kris Says:

    I tried “B” out for the 1st time today and it’s really, really cool! I kept my eye on the car behind me to make sure they noted that I was slowing down and the last few feet I hit my brakes. I was really amazed how fast a charge was put on my battery and as long as no one is too close to my rear I’m using this a lot from here on out. I’ve had my 2007 for almost a month now and I’ve never been this impressed with a vehicle before. I’ve yet to put any gas in it and I actually opened the gas thing today just to see what it looked like under the cover after I remembered where the salesman told me the lever to open it is located! lmao

  2. randygrenier Says:

    You don’t need “B” mode to get regenerative braking. That happens automatically when you lift your foot off the accelerator. “B” mode is only for saving your brakes when going down long hills. In fact, it actually uses power to use the electric motor to create drag.

    Use this link for more info. on “B” mode:


  3. Amanda Says:

    I’ve used the ‘B’ function for stopping my car in the winter. I live in Michigan and our roads can get pretty crappy. It can really help you stop when you’re starting to slide through stop lights and stuff like that. Being that the Prius is lighter than other cars, this is a great function, but I’ve never used it to just drive in. That would drive me crazy the way it slows you down constantly. But it is awesome for winter driving.

  4. XsV Says:

    Randygrenier is correct. I’m a salesmen for Toyota (I know don’t give me any crap) and we tell our customers to really use this sparingly. We tell our customers this because no-one likes relying on something electronic to save their lives, being able to control your braking is somewhat a “comfort” thing. And if not used correctly it can create some trouble. Everyone knows at least how to slam on a pedal! Normal braking on a Prius should not lead to frequent brake pad replacement nor less of braking power than electrical engine deceleration. The pads will last a long time thanks to the electronic advancements with braking and normal braking procedures will also allow for regenerative braking much like the “B” mode. The 3rd generation Prius can also use the “B” mode to go “back” into neutral from drive, as well as “back” from neutral to reverse. Any further questions you may have can be answered by going to Toyota’s main website at http://www.toyota.com/prius-hybrid/demos.html. Here you will find helpful tips on Prius basics as well as full videos on instruction.

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