Brake dust? weird

I think you will find that the mechanical brakes almost always begin to engage at the end of each stop. They also hold the car still while you are stopped on an incline. So, my guess is that it really is brake pad dust. Now, maybe someone else can tell us about the benefits of various brake pad compositions as compared to Toyota's original formula, but yes, I'd say it's brake dust. I use an aerosol product from Armor All called Outlast(TM) Brake Dust Repellent. A small can is good for 4 or 5 monthly applications.

 

i have read that the brakes are applied in concert with the regen, the harder you step on them, the more friction.
not only at the end of the regen, according to those with a scan gauge.

if you think about it, that's still a lot less wear than pads only.

i have never noticed any dust though, but haven't owned a white prius either

 

I almost forgot to mention something important: your pads could be dragging due to calipers needing lubrication. This will also cost you in gas money. I think the standard test is to jack up the wheel and see if you can spin it for one revolution before it stops.

 

All braking under 7 mph is always by friction pads.

Friction pad braking is not just for emergency and battery-full conditions. Prius regen has capacity for only light-to-moderate braking (depending on speed), and many drivers regularly exceed this with their normal medium braking, requiring friction to make up the difference. And as other have pointed out, friction is often used in concert with regen to make braking more immediate and (sort-of, nor perfectly) seamless, so the pads are not fully disengaged as often as you think.

The friction elements can last 'like forever' because careful use of regen can cover a large majority of the overall braking work. But not everyone achieves this. In fact, without changing their braking styles from prior traditional non-hybrids, most drivers won't achieve majority regen.

 

Ceramic brake pads almost totally eliminate brake dust. I installed them on my Plymouth Prowler several years ago and almost eliminates brake dust.

 

If for some reason your in neutral gear, and press the brake pedal, brake pads will engage at any speed. Also in reverse.

 

What I found in 3rd gen Prius, some rear brake pin bolts need re-greasing with Silicon grease, some could jammed and caused premature wear in pads and rotors. For the front brake, they are usually fine, just weird looking corrosion from light use. HOwever, it gets really really hot when you are going downhill in alps or rocky mountains on D all the time. The battery capacity is already too full and the regenerating brakes is stopping and the brake disc gets really hot. Putting to B /engine Braking mode helps the brake fading.