Downshift and parking brake. Actually had this happen a couple months ago with a 2000 Cherokee. Slammed on the brakes and a split second later the pedal dropped. Luckily I didn't have to make that sudden stop after all, and was able to finish the drive dropping the automatic down a gear or into neutral while grabbing the hand brake. It was a brake line that had rusted in one small spot that I never saw.

Also, pumping the brake pedal can sometimes work, depending on failure mode.

Driving an old Ford van they kind with the engine between the seats. You're basically sitting above the front wheels and inches from the front of the vehicle. I'm coming off a side street onto the main street. I'm not going very fast at all. Sure enough brakes fail. I'm pumping like crazy and just seconds from entering the main street. Mere inches in front of me a car is passing the passenger looks up and sees me throwing up her hands. At the last second I make a shar right turn and the I stop.

Had it happen in an Audi A6 on a 70mph motorway. Used the incline of a slip road to slow down while shifting down. Realised I was about 1/2 mile from my destination so drove carefully, leaving plenty of space to use engine braking and used the handbrake to go from 5mph to a stop to park up.

Lift if it’s an EV 🤣

If my brakes failed, I would put the car into neutral (I drive an automatic) and let the car gradually slow down.

I have an automatic that does allow me to manually shift gears if I choose. It isn’t geared well for engine braking but I would do my best to downshift and slow down as much as possible. If it’s safe to do so, or I’m on the freeway, I’d move to the side and use a shoulder lane. Turning my engine off would possibly be unsafe, I couldn’t turn it back on while moving, so I’d have to do my best with the engine. Is it the right thing to do? I dunno but it seems like the most logical in my situation.

Gradually roll to a stop due to friction. Is this a trick question?

Use gearbox and handbrake to effect as much decrease in speed as possible still pumping the brake pedal you never know what might help and pick the spot in the verge to aim for if it's a corner of it's a straight put one side up on the verge to help aid slowing

1967 Pontiac. So high maintenance that brakes are a secondary concern. Power steering would’ve been my first guess. That’s 57 years (2024 - 1967) of brake line flushes. If done every 4 years, that’s 14 flushes. Each takes a heavy toll on the copper lines. Heavens knows what you use as a leaded fuel additive.