You need to change the settings on your car-camera, Souxie. Assuming it works like mine (Eprance mini0801) then in the settings you have an option for how long (in minutes) each block of data should be before a new block is started. On mine I can choose 1 min, 3 min or 5 min, with another option "continuous". If you choose "continuous" the recording is still split into 5 minute blocks but, when the card is full, it will NOT start to overwrite. If you choose any of the timed options ie 1, 3 or 5 min, then when the card is full it will overwite.