Engine Brake?

It is used for downhill grades where you would need to ride the brakes to keep the car from gaining speed. Effectively it uses engine compression to slow the car. As a benefit of the HSD technology, it generates electicity for the traction battery at the same time. On a steep grade, you might end up using both B and the brakes. In a situation where you would shift into B, the engine would already be off..

 

I used the heck out of it driving to Michigan from California. You know when the road is a steep downhill and you see those "Use Lower Gear" signs along the road? That's when you flip it to the "B" position, just as if you were downshifting in a more primative automobile.

The brake lights don't come on in the B mode, also.

 

In my recent trip over 4 western mountain passes I used B mode intermittently. I would let the car coast to 5 over the speed limit and put it in B till I was 2 to 4 under then put it back in D and repeat the process. I would love to here of comments from those more experienced with the car. This mimics what I did with a conventional car when second gear slowed the car a bit much. The B setting does a good job even on a fairly steep grade.