that is not good.. very dangerous.Just purchased a 2013 "MKZ". I wish I would have read the posts here before making my decision to purchase this car. Unfortunately, I can confirm the issue with fuel odor and fuel leaking in the MKZ.
The first night after picking up the Z from the dealer, I smelled fuel in the car and then noticed fuel on my garage floor the next morning. The gas smell was very strong in the garage. I brought it back to the dealer. They kept it a day or two. They didn't inform me of the recall but said they fixed the issue which they thought was a loose O ring.
They filled up the tank for me and sent me on my way. Guess what, I smelled fuel in the car on the way home and yes, gas on my garage floor the next morning. My entire garage had a very heavy smell of gas, the smell made its way into the house!
Back to the dealer. They had the car for a few days and just called me to tell me the car was ready. This time the service guy mentioned something about a recall, I started to immediately research. I found my way to this site!
I really like this car and all the technology and styling. However, had I known about this issue, I would likely not have purchased it.