Minecart with Monster Spawner

Minecarts with spawners are a combination of both minecarts and spawners.

Obtaining
Minecarts with spawners cannot be obtained as an item in the inventory, and can only be placed using the command.

Usage
The spawner inside the minecart acts the same way as normal spawners; but you cannot set the spawning entity even using Spawn Eggs, can only be done thru commands or NBT edits. it has the same associated NBT tags.

More exactly, a spawner minecart acts as a spawner block at the minecart's block position. In other words, if the spawner minecart moved within a block position, the range of spawn would not change.

Drops
When they are broken, spawner minecarts drop 1. The spawner will not drop even though it was in the minecart.

Entity data
Minecarts with spawners have entity data associated with them that contain various properties of the entity.