It doesn't look that bad, but I thought dropping entities in the void was the only way to delete invulnerable and persistent ones; but after noticing some lag, I decided to drop myself with a regeneration V effect, turns out they will continue to fall indefinitely.

Invulnerable carts, or persistent invulnerable mobs are virtually impossible to kill in vanilla Minecraft, which takes out many of their uses.

The only possible workaround for mobs is to give them a regeneration IV effect instead, and a lot of health, but it doesn't work for minecarts.