I recently changed my way of applying boxcars.in this thread, banjo666 suggested to take shots away from the player or NPC. I don't like that, because punishing a player by forcing him to act less is in my opinion and experience a terrible thing. They've already lost 3 shots by failing their attack, so potentially making them not play for an extended period while everyone else is having fun feels really overkill and unfair to me. Unfair as in "not fun". People with a bad initiative roll already suffer of watching the other players play without them, and I don't think it's a fun way to play your failure.
So now, I'm doing this.
IN COMBAT
Success after Boxcars against mooks : The player hits as many mooks as his final outcome allows, regardless of how many targets he had declared (it's still limited to how many the GM says are in range, though : a suggested maximum is 5-6)
Success after Boxcars against Featured Foes and Bosses : The Foe doesn't substract their Toughness from the damage.
Way Awful Failure against anyone (on a failure after Boxcars or from too many -6s) : you take damage equal to the absolute value of your swerve, with a maximum of 5 damage. Don't substract your Toughness. it should be described as the Scroungetech implant shorting out and sending an electric shock, as the opponent blocking your Martial Art attack and injuring you in the process, etc...
If the attack used Sorcery or Guns, you don’t use this rule and suffer the Backlash or Malfunction rules instead.
OUT OF COMBAT
The only way to get a Way Awful Failure outside combat is by getting a negative Action Result (almost invariably from one or more rerolled sixes on your minus die).
Rolling Boxcars works differently and immediately implies that you’re either going to succeed or to fail, whatever your skill and whatever the difficulty.
You roll again, ignoring further doubles, until one of the dice is greater than the other. You don’t calculate the Swerve : a greater positive die means an automatic success (even if your skill was very low), and a negative die means an automatic failure (even if your skill was high enough).