The Great Gatsby, tentatively

Could you please tell me if in the following excerpt from the chapter 7 of The Great Gatsby, by F. Scott Fitzgerald, the word "tentatively" means "of the nature of or made or done as a trial" or "unsure", "hesitant"?

She walked close to Gatsby, touching his coat with her hand. Jordan and Tom and I got into the front seat of Gatsby’s car, Tom pushed the unfamiliar gears tentatively and we shot off into the oppressive heat leaving them out of sight behind.

Thank you.