One of the perks of having a modern vehicle is that you can use devices to monitor the engine and drive train performance.  I was recently using my Vgate Bluetooth Scan Tool OBD2 Scanner to record speed and engine RPM values during a short trip.  In the following plot, you can clearly see the six gears of the automatic transmission as straight lines in speed vs RPM.

The color coding shows the absolute throttle position, which shows 2nd and 3rd gear most used during high acceleration.

Sweet!