George Clooney, Julia Roberts on 'Carpool Karaoke': Why stars love it

Gwen Stefani, George Clooney, and Julia Roberts were the newest guests on James Corden's popular 'Carpool Karaoke' segment, which airs as part of Corden's CBS program 'Late Late Show.' What makes stars want to appear on the feature?

The typically star-studded "Carpool Karaoke" segment on late-night host James Corden's "Late Late Show" program saw even more well-known faces appear than usual during the latest installment.

The musical guest on the latest "Carpool" feature was Gwen Stefani, and along with host Mr. Corden, she was also joined by actors George Clooney and Julia Roberts, who are starring in the upcoming film "Money Monster."

Mr. Clooney and Ms. Roberts hitched a ride in the back of the car during the May 4 episode, which also included Ms. Stefani and Corden singing songs like "The Sweet Escape" and "Rich Girl."

After the duo realized they needed more passengers to drive in the H.O.V. Lane, they picked up Clooney and Roberts and chatted about Stefani's songs and their own movies. 

Corden's "Carpool Karaoke" segment has attracted a genre-spanning mix of bestselling artists, with popular appearances including those by Adele, Justin Bieber, and the group One Direction.

Having some of the music business's most famous names join him to sing in a car is a brilliant idea by Corden, but what convinces singers – and, in Clooney and Roberts' case, actors – to sign on for the segment? 

Besides the obvious angle of promotion for a current project, if they have one, Vogue writer Patricia Garcia points out that the segment makes the stars look like one of us. "Seeing celebrities in a passenger seat makes them seem relatable without feeling contrived," Ms. Garcia writes. "During their drive around L.A., Bieber confessed that he listens to Alanis Morissette’s 'Ironic' in the shower." 

Meanwhile, Guardian writer Melissa Locker believes Corden's enthusiasm in addition to his own musical talent is probably an enticing draw for the stars. "Corden plays the part of a real fan with a deep knowledge of their discography," Ms. Locker writes. "He knows every word as he sings along to their hits.... Corden's ebullient affability is clearly contagious, and the best episodes of 'Carpool Karaoke' happen when the stars lead the fun.... While the host is undoubtedly a fan of his guests and happy to let them take the lead in the fun, he also never seems cowed by the presence of the star in his passenger seat."