Hi, fellow Prius Drivers. I'm curious how other people use their B gear and your opinion of how well it works. Namely, do you use it solely when going down big time hills, or in other more common scenarios? Also, I find that my gas engine is far more likely to kick in after using the B gear, when I would typically be able to cruise on electric. Any help would be much appreciated.
By the way, I was inspired to improve my own performance after reading the article about Wayne Gerdes and other hypermilers in the most recent Mother Jones.
Peace,
Andrew

 

"B" is for engine braking on steep downhill grades, and nothing else.

If you use it other places, you are losing out on regen braking. In a way, you already pointed that out when you said the car would more likely be in ICE mode.

I have noticed the reverse: not using B braking on a short, steep downhill stuffed so much charge into my battery that it turned green on the MFD and I drove the rest of the way home entirely in electric mode.

Harry

 

Just on steep hills where the car speeds up in "D" and I don't want to ride the brakes.

Bob Wilson

 

Really, reallllly long hills where you're confident the battery would get to maximum charge if you left it in "D". I originally thought "B" was max regen braking, but it's wasting downhill momentum to heat by running the engine with no gas. In the majority of situations that's inefficient because you're missing out on battery regen, but if you're coasting downhill 10,000ft, it's a good idea because it keeps you from maxing out the battery then depending entirely on friction brakes.

 

To echo what other posters have said, living in a mountain state, I use the B gear regularly on the long downhill canyon passes I end up in once or twice a week. My first time heading to Park City, however, was a bit traumatic as my battery indicator reached one red (or purple) bar on the way uphill (I thought I killed the car).

However, on the way back down, even with the B gear engaged, I reached full green bars on the battery before I was half-way back down the hill. The really nice feature of the B-gear is that it relieves a significant amount of brake use going downhill, thereby preserving the life of my standard brakes.

I also think the B-gear does a better job of slowing the vehicle's momentum better than the low gears on standard transmissions (I've used both here in the mountains) because it doesn't appear the rev the engine nearly as much compared to the standard transmission vehicles I have driven.

FWIW

UTpiper

 

There are basically 2 schools of thought about B mode. The first has been well represented here and essentially says: don't ever use B unless you are going down a hill and feel that you need the extra braking provided by engine resistance.

I come from the second school of thought which is to use it based upon your needs no matter where you are driving. One major component of B mode is compression braking. Compression braking is common on large trucks. Officially known as a Jacob's Engine Brake. You can tell on the highway when passing a semi if they are running their "Jake". Instead of the normal diesel sound with associated turbo whine, you hear a loud cracking noise coming from the truck. Sounds a lot like an unmuffeled diesel engine. That is compression braking. The driver can choose to engage 2, 4 or 6 cylinders depending on the braking need they perceive. Compression brakes are exceedingly effective at slowing a truck and allow the driver to save a lot of wear and tear on brakes.

Toyota engineers in their brilliance, and faced with the issue of not having any low gears to rely on for engine drag braking, decided to implement a compression braking system on the Prius. And it works very effectively.

My point is that you should use B mode whenever you feel the need for more assistance in braking than just your regular brake. The mode is not limited to any specific geographical condition which may prompt its use. It is also useful for slowing the vehicle down without lighting up your brake lights. You can figure out why that might be useful on your own.

But the best advice is to play around with it and see how it works and get used to it. A good driver is one who is familiar with how their vehicle behaves under all conditions and in all operating modes.

 

...Unless you care about efficiency, in which case using B in all those other scenarios exhausts energy to heat that otherwise would have been used to charge the battery.