context: One ordinary day, 19-year-old Mercer White (Lou Taylor Pucci) steals a Volvo station wagon from a car wash, and leaves Eugene, Oregon to find his estranged half-brother Arlen, who is unaware that their mother has recently died. Soon after leaving, a cell phone in the car rings, and Mercer finds himself talking to the owner of the car, Kate (Zooey Deschanel), who lends him her car on the condition that he calls regularly to describe his trip to her.
  Mercer travels to a bohemian pottery-making commune in Shelter Cove, California where Arlen once lived, but learns that he moved to Reno, Nevada. He passes through Fallon, Nevada to meet up with the seductive Joely (Jena Malone), his middle school crush. In Reno, they take ecstasy and almost have sex before Mercer resumes his search for Arlen. Later he finds himself on the set of a pornographic film, where the director (Julio Oscar Mechoso) tells him that Arlen left to work at a pet store in Sacramento, California. Joely asks Mercer if he can drive her cousin Buddy (Colin Fickes) and his friend Rid (William Lee Scott) to Mojave, California, where they are building their own car. While driving, Mercer finds Kate's YMCA card in the trunk of her car and, now knowing what she looks like, describes a dream to her in which he, Joely, and Kate are dancing in a re-enactment of Bande Ã  part's dance sequence. Not wanting to get sidetracked, he tries to leave the others behind in a motel room, but when Buddy threatens to steal the car, Mercer tells him that the car belongs to his girlfriend, and Buddy, Rid, and Joely leave without Mercer in Kate's car. He hitchhikes to Mojave and finds the salvage yard where Buddy and Rid are working, and retrieves the car.
  Mercer talks to Kate while driving, imagining her sitting in the back seat of the car, but she hangs up in jealousy when he mentions Joely for the first time. He arrives in Sacramento and finds the pet store where Arlen worked. The owner (Maura Tierney) asks Mercer to sing in her children's band, for which she plays as part of her probation. When he returns to the car, he finds somebody trying to break into it, only to discover that it is Kate. They spend the night at a hotel, but he leaves without her the next morning and catches a train to Los Angeles, California. With the help of a translator, he phones Arlen's last residence and learns from a Hispanic woman that Arlen is working at a hotel in Ensenada, Mexico. Mercer finally meets Arlen (Jsu Garcia) at the hotel in Ensenada, but Arlen assumes Mercer is just there for money. Enraged, Mercer tackles his brother to the ground and gets kicked off the premises. Kate later finds a bloody Mercer sitting on the side of a road and takes him to a hotel. She tells him that she let him take her car because she was attracted to him, and they have sex. The next day Mercer meets with Arlen again, more amicably, and tells him that he and Kate are driving to Louisiana to spread his mother's ashes.
question: Who is the car's owner?
answer: Kate