There actually is a part in the rules, DS, where it states you must inflict damage to be able to cause the effect(s). Now with attacks with a max DV of 1, clearly this cannot be a restriction before soak, otherwise those shots would never actually work. So likely this means that the DV, after soak, is capped at that value. So you had 2 net hits which allows you to cause 1 effect, pick engine block destruction, do 12P, the car soaks 9, damage remains before the cap so the engine block got smashed and 3 damage was also inflicted.