2016 Toyota Prius: Cruise Control Idiosyncrasy
by Jason Kavanagh, Engineering Editor on July 7, 2016
You'd be mistaken if you thought that the photo above indicated that our long-term 2016 Toyota Prius allowed cruise control to function when the "gear" selector is in B mode.
Because it doesn't.
If you're in B mode (this mode delivers increased regenerative braking action) and turn on the cruise via the little button on the end of the stalk, the main cruise icon illuminates in the instrument cluster. The display shown above flashes up momentarily. "Great!" you think. "In mere moments I shall command the vehicle to maintain my desired ground speed independently of my right-most lower torso appendage! Fantastic! I shall call this phenomenon 'cruise control'! Sorcery!" So you bump the stalk downward to set your speed, and, in a triumph of modern motoring, nothing happens.
That appears to be the long and short of it. If you select D mode (this mode delivers less regenerative braking when you lift off the accelerator) and follow the steps described above, the cruise sets normally. Switch back to B, nothing.
I'm trying to think of why Toyota chose to disallow cruise control when in B mode. Maybe (and this is only a guess) it has something to do with larger variations in set speed after long, steep descents. If the cruise is set, B mode would recharge the battery in less time than D mode would, and then the cruise will have to motor the engine sooner to provide engine braking... but perhaps the max engine braking effect delivers less retardation than does B mode, so the engineers just disallowed the combination. Yeah, it's a stretch.
Whatever, I want both increased regenerative braking upon lifting AND the cruise to function, all at the same time. I imagine others would, too.
Jason Kavanagh, Engineering Editor @ 3,317 miles