Wait, do regular cars engage the emergency brake in a fail-safe way? I've always treated the emergency brake as a way to keep a stopped car from moving, not as a way to make a moving car stop.
No, a regular car will not engage brakes without human interaction. The fail-safe is having two independent systems - hydraulic for the foot brake and wire rope for the hand brake in most vehicles.
Additionally automatic transmissions have a transmission lock, but that won't work while the vehicle is in motion.
Some modern cars use electric systems for both, I'm not sure how that would work.
Also, the hydraulic brake system is built with redundancy (dual circuit), so even a sudden big leak in a brake line will leave you with some braking power.
And the power braking system, being pneumatic IIRC, keeps working for a couple of hard stomps on the pedal even if the engine stops running and you lose 12V.
Pretty much the only thing you can expect to lose is the ABS. Even then, I understand that system has a failsafe such that it keeps the car from spinning in the event of malfunction and brake lockup. You can see this in ABS-related accidents as straight skidmarks. But I don't think that works when you've lost electric power.
Edit: actually, the recent Koenigsegg One:1 high speed crash (driver not hurt) during testing at the Nurburgring was an ABS sensor failure, you can see the hallmarks in photos. Koenigsegg also deserve big props for having been completely open about it.
No, the handbrake (not emergency brake) is actually connected (mechanically) to a completely separate set of brakes on the rear wheels. Only on custom-built drift cars รก la Ken Block is the handbrake connected to the normal brake calipers.
It depends on the car. Some of them engage the same calipers the hydraulic system uses. Some have a separate caliper or drum. Older, drum brake cars engaged the same shoes the hydraulic system used. And if you go back far enough, some had mechanical pawls or band type brakes that engaged at the transmission.
And drift cars use a separate hydraulic brake attached to the rear disks.
This is correct. Some emergency brakes uses a screw mechanism to activate the brake cylinder piston to push on the pads. Same stopping mechanism as if you push on the brake pedal.
Others (usually less expensive cars) have a set of drum brakes inside the disk brake that act as emergency brakes.
If you have rear drum brakes, it's the same as my first example. The emergency brake activates the normal braking system.
Additionally automatic transmissions have a transmission lock, but that won't work while the vehicle is in motion.
Some modern cars use electric systems for both, I'm not sure how that would work.