Tegan and Sara are working hard on their upcoming album, and the Quin sisters are keeping fans in the loop with weekly webisodes about the recording process. On the latest episode of their 'Carpool Cofessionals' series, which finds the twins traveling back and forth from the studio, the 'Walking With a Ghost' musicians talk about their vocals on some tracks and their love for Sia, all while engaging in some comical, sisterly banter.

After realizing that they were wearing the same coat as one another, Tegan and Sara let fans in on some details as to what the instrumentation will sound like on their 2012 release. "[Our drummer is] not showy or dazzling or anything… like he's not like wind chime, wind chime, wind chime, wind chime," Sara said while showing off some intense air-drumming skills.

Tegan continued to talk about the music on their forthcoming LP, saying, "We're going to this great studio East West that we've been talking about all week, that's been awesome and really weird all at the same time." She went on, "Now we're gonna [record some] piano, because they've got a big beautiful piano room with a Grand piano in it. And then hopefully we'll be done midday and head back to Greg's studio and start vocals."

After cutting some vocals on a song, Tegan told her sister, "Well I thought you sounded great today. You sang beautiful harmonies -- it was my song today, like my lead vocal, I should say -- and you did a great job. You sing lead in the bridge, you wrote the bridge and it's great. This is a collaboration, Sara!" It's great to hear that girls are writing together again, since it proved to work out well on 2009's 'Sainthood,' which marked the first time both Tegan and Sara actually co-wrote tracks together.

At the close of the video, Tegan and Sara took turns paying compliments to their friend Sia, who visited them in the studio during a recording session. "Sia came to visit us, too bad we didn't get her on the show," Tegan said. "She popped in and belted it out for a while, helped inspire us." After chiming in with some really awful a cappella vocals (purposely, of course), Sara said, "That was us [singing], and then Sia came in and killed it and we were like, 'Sia, go away now so we can try to sing like you, but not in front of you."

Watch Tegan and Sara's Carpool Confessional: Episode 2