Hello,

I own a brand new Mazda3 (3rd gen), 2 litre 6-speed automatic variant and drove about 650 miles with it. There's a strange behavior regarding the braking system which I can't tell for sure that I had with my previous vehicles.
When I shut down the engine, I can pump the brake pedal about 5.5 times before it becomes rock solid, which is ok. However, if I shut down the engine and leave the vehicle for 12 hours or a day (without touching the brake pedal), when I come back in the next morning and press the brake pedal again (in order to start the engine), it seems like I able to pump the pedal only 0.5 or 1 time before it becomes rock solid and this is what worries me. Once the engine is running, the brake pedal returns to normal and it seems like there's no difficulty in slowing down nor stopping the vehicle.
As far as I can remember with my previous vehicles, the vacuum that remains in the braking booster after I shut down the engine should last for days, even weeks or months not a single day or few hours.

Is this normal?

 

No, I do not believe that is normal. our 2016, also a Gen3 model, can go many days, even a week or more, and the brake pedal is still soft for at least a pump or two (never tried beyond that).