Sia joins James Corden for the latest segment of the Late Late Show's Carpool Karaoke where the two wear wigs and sing several of Sia's hits like 'Chandelier,' 'Diamonds.' 'Titanium' and 'Elastic Heart.' After picking the This Is Acting popstar up by the side of the road, James also uses to opportunity to ask Sia why she wears wigs, a little about her singing technique and why she believes in aliens.