Command Minecarts calculate as 1 block above where they are

When you use a Command Block Minecart to run a command using relative coordinates, the coordinates ~ ~ ~ are 1 block above the minecart, as opposed to on the block of the minecart. For example, if you wanted the cart to replace the block that it's rail was on with stone, you would have to do ~ ~-2 ~ instead of a more expected ~ ~-1 ~