Britney, 34, strapped in and took a ride around the streets of Los Angeles in James' 4x4 as they belted out her classic hits including 'Oops I Did It Again', 'Womanizer', 'Toxic', and they even donned matching school shirts and plaits for a rendition of 'Baby One More Time'.
But it was her revelations about her love life that had us gripped. After chatting about their children, Britney told James: "I want more. I'd like three more," but added: "I have to find the right guy first!"
Britney already has two boys, Sean, 10, and Jayden James, nine, with her ex husband Kevin Federline.
Having had a rocky love life over the years, she went on to express her frustrations about the opposite sex and how having two failed marriages - including one in Las Vegas to childhood friend Jason Alexander that lasted just 55 hours - has put her off tying the knot again.
Britney most recently dated writer and producer Charlie Ebersol for eight months, who went on to date Tiger Woods' ex wife Lindsey Vonn within months of splitting with Britney last summer.
"I think I might not ever go to men again. I don't think I'll do the whole man thing anymore or get married, I'm just done with men," she told James. "I may french kiss someone, but I'm not going to marry anyone, I don't believe in marriage any more."
Watch the full Carpool Karaoke here...