It is a simple question with the goal to evaluate how do you think and how you approach defining the problem. What interviewers are looking: 1- asking clarifying questions/understand your customer. 2- understanding goals and objectives, problems to solve, value. 3- make trade offs during the design. 4- documenting scenarios, use cases, requirements. What interviewers are NOT looking for: - how much you know about designing something (cars in this case) - how much technological knowledge you have - the "right" answer