High pitched whine from rear of car

My 2009 Camry with 72k on it has started to make an intermittent high pitched whine from the rear of the car. It’s only noticeable while accelerating or maintaining speed. Any ideas?

The only thing back there that could account for a whining noise is the fuel pump, and before they fail, it is not unusual for an electric fuel pump to begin making louder noises. I suggest that you have the fuel pump checked right away, before you wind up stranded somewhere.