I needed someone to create this thread before I bought my Cruze. I read some articles about the car, visited a few dealerships after hours to see a Cruze 'in the flesh' without being 'helped', and then I test drove one to see how it drove, and sounded, and felt. Then I made the decision to buy a Cruze, and I decided which model and color I wanted. Fortunately the exact car I wanted was sitting on my nearest dealer's lot! I showed up and told the salesman I was interested in buying THIS car. We discussed the price, he gave me the keys and left me alone to explore the car. I wanted to sit in all the seats, look at the trunk and the engine compartment, and see how things opened, turned on, adjusted, etc. I figured out just about everything on my own EXCEPT how to open the fuel door! I couldn't see anything on the door which indicated how it opened from the outside, so I searched the passenger compartment for a release lever or button. I have a similar looking fuel door on my 1988 Fiero GT, and it has a release lever. I did try pushing on the door, but I didn't use enough pressure to open it. I didn't want to do the wrong thing and break something (especially since this was going to be MY car!). So when the dealer asked if I had any questions, I did have one for him.
How to get to the gas cap....
Go to the round door located on the passenger side rear quarter panel.
Imagine the door has a clock face on it, and put your finger where the '9' would be. Use a clean finger or thumb, not a rock, or car keys, or anything with an abrasive surface, or you will scratch the finish on the fuel door.
Push down on the '9'. Not 'down' toward the ground. Push on it as if your intention was to stick your finger through the side of the car. As though you wanted to touch the driver's side rear tire.
Continue to push with a firm pressure. You will need to apply more pressure than you need in order to type text messages on your mobile device, but less pressure than is required to do a pushup. Try to do a pushup so you will be able to compare.
If you do this properly, the fuel door will give way, moving inward, and then stop. When it stops moving, release the pressure you are applying (pull your finger back toward your body).
The door will open, revealing a secret compartment containing a fuel (gas) cap.
I am exhausted, but I am glad to have contributed. I will leave it to someone else to create related 'how to' threads (like 'how to remove the gas cap', 'how to put fuel into the car', and 'how to close the fuel door').
And in all seriousness, let me say that I love this forum. It has saved me time, money, and frustration. I appreciate all of the sharing of information, and I hope that you'll take this message in the spirit it is created - with love and the sincere hope that it will make you smile.