Your interviewer wants to know whether, as a representative of their brand, you would be 'on-brand.' You never have a second chance to make a first impression. So thoroughly familiarize yourself with CarMax's brand. As they state on their website, "We have our customers' backs. We treat everyone with respect. We strive to deliver the best product and experience. We value integrity above all else. Our customers: We put integrity and transparency at the heart of every interaction with you, whether that interaction is online, on the phone, or in person. We are committed to bringing clarity to each decision you make so you can feel confident about buying the car you love - and enjoy the ride while you do it."
