Going back to IR for a moment, getting a directional fix on a single IR beacon is not much harder than a light following robot technology, and you just need a couple of transistors for that -- I just did that
You could filter the signals coming into a pair of IR phototransistors for the carrier frequency of the beacon and if the left signal is stronger than the right, drive the right wheel forwards etc. and it will home in on the beacon.
Put a proximity sensor on the beacon so that when the robot car arrives, the beacon turns itself off and turns the next beacon on, so off the robot goes towards the next one etc.
If thats not good enough, and you want the car to be smart enough to know which beacons its visited, and have multiple beacons transmitting at the same time, then you are looking at a project that IMO is far beyond your, mine or the Arduino's capabilities.