i was looking at these specs for a car that say stopping distance is 120 feet... i'm assuming that is from 60-0 (mph), but how is that test taken? with the clutch disengaged, the car would stop faster than it would with the engine power still pushing forward. any ideas?

0-60mph
Slam on brakes
Measure distance it took to stop
Profit

I don't think there is anything more to it as it would make the test unfair. It is tested to see how long it will take you to stop if you have stupid people jump out infront of your car, and you only have time to brake.

Dont take it for the exact answer though, as it is my opinion and it can be wrong

120 feet sounds right to brake to a halt from 60mph.

While engine braking is useful when braking gently, I suspect it would only be a hindrance when performing threshold braking (at least all my simulated results point it to being slower).

Quote from bunder9999 :

i was looking at these specs for a car that say stopping distance is 120 feet... i'm assuming that is from 60-0 (mph), but how is that test taken? with the clutch disengaged, the car would stop faster than it would with the engine power still pushing forward. any ideas?

Going down the gears engine braking would be smoother and quicker than just declutching.

Quote from ajp71 :

Going down the gears engine braking would be smoother and quicker than just declutching.

Smoother yes, quicker no, assuming your brakes are in order. Engine braking can not magically transfer more negative acceleration through the wheels/tyres than good brakes can.

Does the braking distance include driver's reaction time?

Quote from breadfan :

Does the braking distance include driver's reaction time?

No, but the stopping distance does

In this 0-100-0 run in an Ultima it does sound like they just pop the clutch in on the way back down.