Hmm, not sure about this. My Mitsubishis is an auto (i'm using it today) and it definitely has engine braking - even more so if I drop drop the overdrive button on hill descents, or put he gear lever into '2' or '1'. I never leave it in drive at lights unless momentarily stopping as this heats up the transmission fluid (and reduces MPG) and can on hot days mess with the torque converter lockup speed on the overdrive (which affects MPG again)
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I have been shunted a couple of times in the past. One time the car was shunted nearly its entire length when I pulled up to a red light in the rain and the car behind me thought I was going to run it

. It wrote ff the front of her Maestro, but as I has a towbar on mine, got away with a cracked rear fog lamp.
My experiences are that the impact happens so fast, you habve either already enough pressure on the pedal or not, and a foot slipping off would be very much an 'after the event' action.