send array of integers via xBee s1

I need to have always the more recent data sent, so that the car has the latest command i gave her, If the buffer fills quicker than arduino reading it's data I would have always an encreasing delay from my commands and what the robot does, isn't it?

Now as I'm writing about this I've thought:I could add a part of code that sends an "ok" when it's ready to recive, so the ground station sends it's data and the car recive only those one, leaving the buffer clear when I don't need data and ready to recive as I have to use them. would that work?

My first idea was: ground station continues sending data, car reads the latest sent. I clear the buffer so that the data aren't too old
Now: car needs data, send a byte to the G.station, which sends back the array of data needed. No useless communication, no buffer filling up with data i don't need ,as you said, REALLY the latest data availale.
Right?