how to use "b" for driving.

Please post your results of using "B" and not using "B".

Saturday I drove on a windy road in the foothills of Colorado (285 from Morrison to Evergreen and back for those that know the area) and I expected to use "B" for the first time. I found that I didn't need it. Because of the sharp turns I was actually going the speed limit (~30 mph, 20 mph on some turns). I was in stealth most of the time (on the way back down, that is) and didn't have to brake much. I was almost disappointed that I didn't have to go to "B". Guess that will have to wait until I go on a longer trip into the mountains.

 

"B" is like downshifting to slow the car down when going down steep inclines in order to save the brakes. Since the car must use the engine to do this, it will use some gas. For coasting, the car is in pure electric mode if it is on at all (other than recharging the battery) and therefore is a more energy efficient mode. I have had my car since Dec 24 and have not had an occasion to use the "B" mode yet. I'm certain that if I take
I-70 west from Denver into the mountains that I will have to use "B" mode to slow down the car on those extremely steep grades. It actually surprised me that I DIDN'T have to use it on the way down from Evergreen.

 

From what I understand, when you're in "b" mode and you're coasting (foot off of the gas pedal), you are braking - engine braking.

 

I have found that when using B for extended periods (2-5 mile steep grades), occasionally the engine will rev very loudly (as if to object).

I also find it interesting that if you ride B to a complete stop the engine will not shut off. You must put it in D or P for that to happen.

 

Out of curiousity, what does the Energy Monitor for current mpg state when you are going down those steep declines in "B" mode?

For instance, in "D" mode, it would recharge the battery to full green and state 99.9 mpg.

 

Another crazy question on braking while going downhill.

If you set the cruise control at a slow speed, but fast enough to engage the cruise control, and then go down a hill. Is the Cruise control smart enough to use regenerative braking to keep the car at the set speed? Would this be more efficient that "B" mode or using the brakes?

 

I've found the "B" mode to be completely unnecessary. I've had my Prius over Raton pass on the CO/NM line. The grade is a 6 to 7 percent grade. The car absolutely held its set speed on the cruise control, even going downhill. The only time you should use "B" is if you are going over a particularly steep grade, and need the extra assistance in holding the cars speed in check. There is NO economy enhancement in "B" mode.