Quick tip, you can do this much easier by shifting the Volt into neutral and then braking. In D and L, the volt actually produces very significant braking via regen via the brake pedal, so much so that you'll have to really brake hard to get any friction braking action. In neutral, regen is turned off and all brake pedal travel is actually physical brakes. You'll be able to clean off your brakes once in a while with just casual easy braking if done in N. Even if you keep your same procedure you use today, you'll get more effect doing it in N.