You underestimate what "downhill" can do to that equation. I recommend looking at some roads in WV like route 60 to the east of Gauley Bridge, Mount Alpha Road in Kanawha City, or Goff Mountain road that connects Institute to Cross Lanes, on the end near Institute. That last one has a hill steep enough that just sitting in neutral will get you up to 60MPH before you reach the bottom without heavy breaking.

I used to claim my state didn't have any bad drivers, because there are too many places where if you fuck up you're going to fall a.couple of stories and get impaled on a tree.

First to clarify, you mean with the clutch pedal "out." Pushing the pedal down actually disengages the clutch, ie forcing the plates apart to disconnect the engine from the transmission.

In a gasoline powered car that is in gear, yes there is a braking effect. Diesel engines don't, which is why semi trucks have a thing called a Jake Brake.

Also, depending on what went wrong with your engine/why it is shut down, you may not want to choose to do this.

Yeah, in a manual car with the clutch disengaged and a gear engaged (and obviously the gas pedal disengaged), it should brake a little bit on its own. Many people don't even use their parking brake, unless they're parking on a slope, because that braking effect is good enough.

But I don't think, you'd even need this braking effect. You can apply a lot of force to that brake pedal, if needed. I was taught, that if I need to brake for an emergency, I should kick, with full-force, the brake pedal and the clutch.

Not entirely sure, why that's advised, maybe to avoid having the engine stutter or shut off, but I assume you couldn't raise the brake amplification much more than that anyways (especially not without the driver being lifted off their seat and losing control).

The amplification is more of a comfort feature, since it means you barely need to move your feet in every-day-traffic.