Britney Spears did a lot of giggling, chatting, dancing and mouthing-along to the lyrics during her Carpool Karaoke segment, but not a whole lot of singing.

The pop superstar hopped in the car with James Corden for his viral segment, but she seemed guarded during the nearly 10-minute bit.

George Clooney, who spent a few minutes in the backseat during Gwen Stefani’s Carpool segment, let loose more than the “Toxic” singer.

While stars are known to get silly during Corden’s drive – Adele rapped Nicki Minaj lyrics and the Red Hot Chili Peppers took their shirts off mid-ride – Spears seemed to hold back, often letting Corden belt it out as she sang quietly if at all.

During the segment’s last song, “Baby One More Time,” Spears finally seemed more at ease, with the “Late Late Show” host in a schoolgirl outfit beside her.

Spears’ singing – or lack thereof—didn’t go unnoticed in the Twitterverse.

Still, some found Spears' passenger's seat performance to be entertaining.