A vehicle-mountable track-lighting light bar (16) supports multiple light modules (5) in user-configurable mounting positions, each of the multiple light modules having a mounting foot (160), electrical contacts (300), and laterally extending track-attachment members (330). Multiple laterally spaced-apart electrically conductive pathways (274) are supported on a floor of each of light module mounting tracks (110, 112, 114). A light module, when its mounting foot is set in a light module mounting track, is slidable lengthwise along the track length while its electrical contacts contact associated ones of the electrically conductive pathways. A controller (276) is electrically associated with the electrically conductive pathways so as to apply electrical signals for delivery to the electrical contacts of the light module.