"I would not be happy with this on my car, especially if I was holding it on the brake pedal on a hill."
You would not need to press the pedal hard to hold it on a hill, try it !
As for "as there are are no compressable parts" there is a little give in all parts, the brake pressure is climbing due to the vac pump as per Aidan,s post even if you are not pushing harder on the pedal.
Kev.
Copyright © uk autotalk