Mine cart disembark does not teleport player away from mine cart using cardinal diction. Actually you do not teleport away from the mine cart at all, A minor bug but it breaks all auto transportation builds that require the play to be teleported away from the space in which the mine cart resides, like the mine cart vertical elevator. Tested in vanilla with no issue

This is how the mine cart is supposed and behaves in vanilla. Excerpt from http://minecraft.gamepedia.com/Minecart

"Players can exit the minecart by pressing sneak, however if there is only one block of headroom above the cart the player will take 1 (Half Heart.svg) of suffocation damage as his head will be temporarily in the ceiling. When the minecart is exited, it searches for an adjacent or diagonal 2×2×3 area to put the player 1.5 blocks away from the cart."
Below is what seems to be happening all the time

"If none is available, the player is deposited directly above the minecart. Consequently, the player falls inside the minecart."

There is a known bug about mine cart exiting where you are unable to exit in the cardinal directions South, South East and East. It's similar to this but I could not locate the exact bug reference.
https://bugs.mojang.com/browse/MC-51987