I was wondering, is it possible to control multiple RC cars with one Arduino micro-controller autonomously in perfect tandem or any other way related to this?
Also, could an Arduino be used as a controller that would have two RC or Bluetooth controlled vehicles perform different tasks at once?
Controlling vehicles by a computer without any feedback is almost impossible. Each vehicle can react a bit differently on the same commands. Try to make one vehicle drive some route under computer control, then repeat that program and watch how close the vehicle stops at the same end point.
If you use nRF24L01+ wireless transceivers then the communication part will be straightforward.
As @DrDiettrich has said, getting the cars to do what you require will be difficult and may be impossible without a very sophisticated on-board control system and on'board sensors.