Learn how to open the gas door and cap in a 2010 Toyota Prius in simple steps. Locate the remote fuel filler door which can be found on the floor next to the driver seat. Pull the lever up to open the fuel filler door. Remove the cap by turning it slowly counter clockwise and hang it on the filler door. After filling the recommended fuel place the cap and turn clockwise till you hear a click sound. Finally lock the fuel filler door to finish.