This new gadget is ready to pump the brakes on bad drivers. New “speed limiter” devices for cars are set to force reckless drivers with multiple violations to finally slow down, by linking to their ignitions and capping how fast their car can go with the help of GPS technology, The Post has learned. The new units — which could be forced into the cars of some 3,000 bad drivers at $1,000 a pop under a proposed state law — was giving a test drive Wednesday for reporters. The units gave a glimpse