Flood Cam Picks up Cat, not Vehicle

Hello,My flood cam has stopped detecting our charcoal colored vehicle. The cam picks up a cat when its set to "People Only Mode", it picks me up walking the dog in the morning, it picks our silver vehicle, but for the several days, the cam will not pick up the arrival or departure of our dark colored vehicle. I've made adjustments to the sensitivity, toggled the "people mode" on and off and it still doen't pick up the car.Any suggestions?Matt