The veteran defender arrived in the summer from Borussia Dortmund, but wasn't playing regularly until coach Claudio Ranieri's appointment.
“I had difficulty initially. It is an enormous city, very beautiful and with an incredible history,” Hummels told Voce Giallorossa.
“However, it took me a while to understand Roman traffic rules. It was really very stressful for a few months.
“Having said that, I was recently told that I am already driving like a Roman, but I think that might’ve been a bit of a disguised insult rather than a compliment…”
Asked about next season, the 36 year-old said: “I don’t have to decide in the next few weeks. In recent years, I have listened to my body, to my family and my son, because I do miss spending time with him.
“This is why I will only make a decision in the summer. There is a lot of responsibility having a seven-year-old son, but I think we’ll find a way to be happy.”