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Hi all,

I am a 3rd day Prius owner. I accidentally drove with the engine brake on (B-gear) for about 25-30 miles - and, no, there wasn't that long of a downhill stretch :)

I am the first to admit I am not a car guru; so could that cause any long term damage to my car, specifically around reducing my MPG?

Thanks,
- Joel
 

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Yup, and I did the same on my first "test drive". Put it in "B" to see how it ran, and forgot to take it out of "B". And I wondered why I couldn't get very good mileage.

Maybe Toyota should put in a bit flashing "B" on the dash for us "older folk". ;)

I'm told all "B" does is enhance the regenerative braking - comes on sooner and harder, does so without the brake pedal being depressed, and lessens the "coasting" of the system, perhaps to nil.
 

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It does more than that though...it forces the ICE to stay on in times it would otherwise shut off (any time you engage it while going more than 20mph), so you don't get the benefit of ICE shut off.

Any time you take your foot off the gas B-mode basicly begins the braking process taking away your coasting distance and forcing more accelerator use to maintain speed and distance.

And it just plain feels aweful....lift your foot off the gas and it feels like someone slammed on the brakes.
 

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"B" mode

Having never used it in my usual driving I can't speak to how it does on relatively flat terrain but I can say that for long slow winding downhill driving the "B" mode works wonderfully to keep you from having to ride the brakes almost constantly. We were recently in Yellowstone and there are some roads where just such a long downhill 20 to 30 MPH driving is what's called for and the "B" mode was exactly correct for those conditions. I didn't notice any deviation in acceleration for those few segments that were uphill but, again, the downhill use of "B" was very nice.
 

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You can coast, you just have to press on the accelerator more to cancel the extra regen drag.

I forgot about the ICE not stopping in B. You don't have to exceed 20MPH for that to happen. I have been at stops and ICE was still running until I switched back to D.
 

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DanMan32 said:
You can coast, you just have to press on the accelerator more to cancel the extra regen drag.

I forgot about the ICE not stopping in B. You don't have to exceed 20MPH for that to happen. I have been at stops and ICE was still running until I switched back to D.
Let me clarify that.

If your ICE is running at any speed and you go into B-mode, it will continue to run, even if you stop, until you go back into D (or R?)

If you are going faster than 20mph in stealth and go into B-mode the ICE will start and continue to run.

If you are in stealth at less than 20mph and enter B-mode the ICE will not start.
 

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efusco said:
If your ICE is running at any speed and you go into B-mode, it will continue to run, even if you stop, until you go back into D (or R?)
Does that work for N too? I remember pulling into the carwash and put the car in N while the ICE was running. I was surprised when the ICE run through the entire wash!
 

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I experimented with that a while back. Yes, ICE remains running if shifted to N. Of course ICE will remain off while shifted to N, since the MGs are disabled, which are what is needed to start the ICE. Also, even if ICE is running in N, it's simply wasting energy, since the MGs are disabled from being generators as well.
 

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DanMan32 said:
I experimented with that a while back. Yes, ICE remains running if shifted to N. Of course ICE will remain off while shifted to N, since the MGs are disabled, which are what is needed to start the ICE. Also, even if ICE is running in N, it's simply wasting energy, since the MGs are disabled from being generators as well.
Thanks, DanMan. Ok all you MPG junkies out there, if you're shifting into N while you're moving to cancel regen, make sure the ICE isn't running when you do it. Your max MPG will only be around 200 and not infinite like you thought.
 
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